Not that I ever remember seeing. There is no mention of Epicureans in Thessalonians either only in Acts. And those Epicureans just say WTF about Paul's teaching.
I've personally chalked this one up to Dewitt's penchant for writing embellished historical fiction.
PS: I have no problem with DeWitt's historical fiction, but I find that in checking the citations in Epicurus and His Philosophy that he'll sometimes take a tiny detail or one word and extrapolate a whole story from that. This might be one of those instances unless someone knows where there is mention of Peace and Safety as a greeting or motto in the Epicurean texts. I'll happily give a mea culpa.
I've personally chalked this one up to Dewitt's penchant for writing embellished historical fiction.
I think I agree as to this "Peace and Safety" watchword business. I think it's a reasonable extrapolation, but it needs to be clearly considered to be that.
In earlier years I tended myself to use that phrase a lot and I think I used it frequently at NewEpicurean.com. However I've consciously stopped doing that in recent years, and I am about ready to deprecate it entirely, especially since it doesn't fit well with the "warrior Epicurean" approach that I think is more accurate. It might also possibly be a phrase that the Christians were using in a deprecating manner, which is an aspect that DeWitt might not have approved of in the way he described it.
All in all I think this is one of the examples that I would most frequently cite as a point of departure between me and DeWitt.
I don't think it's totally harmful, and I can see the strong attraction of wanting to give people who are familiar with Christianity a reason to be interested in Epicurus, but I do think this is overplayed.
I haven't pulled out DeWitt to check the reference before writing this, but I definitely agree with this:
This might be one of those instances unless someone knows where there is mention of Peace and Safety as a greeting or motto in the Epicurean texts. I'll happily give a mea culpa.
A similar instance is DeWitt's "sound mind in a sound body" which I think is more likely to be accurate and representative, but which might be an embellishment to imply that it was a formulation that the Epicureans used. It's a pretty obvious concept and the more obvious something is the less likely I think the Epicureans would have considered it something unique to them.
Rather than "Peace and Safety" it is more likely that Epicurus' motto was "Total War Against the Establishment!" 
A similar instance is DeWitt's "sound mind in a sound body" which I think is more likely to be accurate and representative, but which might be an embellishment to imply that it was a formulation that the Epicureans used. It's a pretty obvious concept and the more obvious something is the less likely I think the Epicureans would have considered it something unique to them.
I'll give Dewitt that the Epicureans had that concept: health of the body and the serenity of the soul/mind/psychē (Letter to Menoikeus).
Just one example from Epicurus and His Philosophy.
There are numerous "peace and safety" references in EaHP, but this will do to illustrate my point. Citation 117 simply points to Lucian's Alexander the Oracle-monger, 25:44-46. 118 just points to I Thessalonians 5:3. That's it. And I believe most of not all of the other "peace and safety" point to the same Bible verse.
I think I agree that DeWitt's reach exceeded his grasp on this point. It is far from settled, in my view, that "Peace and Safety" was a watchword among Epicureans. But it ought not be controversial that these were important, and they were often presented as a pair:
Peace and Safety
But nothing brings more joy than to live well
in serene high sanctuaries fortified
by wise men’s learning—where you can look down
on other men, see them wandering around
in all directions, roaming here and there,
looking for a path in life, competing
in their natural gifts, striving for honours,
seeking with all their effort night and day
to rise to the top, to win great power.
O wretched minds of men, O blinded hearts!
In what living darkness, what great dangers,
you spend your lives, however long they last!
Do you not notice nature barking out
her one demand, that pain be kept away,
divorced from body, so that, free from care,
free from fear, she may derive enjoyment
in her mind from a sense of pleasure?
Hence, we see that for our body’s nature
only a few things are truly needed—
the ones which do away with any pain.
-Lucretius
It is not the young man who should be thought happy, but the old man who has lived a good life. For the young man at the height of his powers is unstable and is carried this way and that by fortune, like a headlong stream. But the old man has come to anchor in old age as though in port, and the good things for which before he hardly hoped he has brought into safe harbor in his grateful recollections.
-VS 17
There is no advantage to obtaining protection from other men so long as we are alarmed by events above or below the earth or in general by whatever happens in the boundless universe.
-VS 72
And yes, Lucian;
The fellow had no conception of the blessings conferred by that book upon its readers, of the peace, tranquillity, and independence of mind it produces, of the protection it gives against terrors, phantoms, and marvels, vain hopes and inordinate desires, of the judgement and candour that it fosters, or of its true purging of the spirit, not with torches and squills and such rubbish, but with right reason, truth, and frankness.
For the end of all our actions is to be free from pain and fear, and, when once we have attained all this, the tempest of the soul is laid;
-Letter to Menoeceus
And in a similar vein:
Know then, that the only aim of the knowledge of the heavenly phenomena, both those which are spoken of in contact with one another, and of those which have a spontaneous existence, is that freedom from anxiety, and that calmness which is derived from a firm belief; and this is the aim of every other science.
-Letter to Pythocles
Great research Joshua thank you! Aside from the merits of the point, which I think you're exactly right on, I guess I should add that even where DeWitt goes full-bore extrapolation, I'd say his extrapolations are never so wild that they deviate from the core of the philosophy. DeWitt may tend to see it in places that not all of us agree it really exists, but I'm not sure I am aware of a single instance where what he claims to be seeing is something other than an Epicurean doctrine. Both "peace and safety" and "sound mind and sound body" are surely points that Epicurus was teaching in some form.
