QuoteAnd the atoms move continuously for all time, some of them falling straight down, others swerving, and others recoiling from their collisions.
And of the latter, some are borne on, separating to a long distance from one another, while others again recoil and recoil, whenever they chance to be checked by the interlacing with others, or else shut in by atoms interlaced around them.
Maybe I am wrong to think that commentators assert that the swerve is not in Herodotus, because Bailey uses that word in the above excerpt from his translation of it. Or maybe its really a different word, or the point is that Lucretius' version is significantly more detailed.
The letter also says that the universe as a whole is now as it always has been, so maybe the thought that there was ever a "first" swerve leading to the atoms getting entangled is the inconsistent piece, and maybe that was and remained Epicurus' own position.
I would think Epicurus would have held tightly to the view that while we can look narrowly at "local" events as having "firsts" and "lasts," that as to the universe as a whole there is and never has been anything truly new.