The reason I did it the other way in the first place is that i think it might be slightly better from a balance point of view to have the first big graphic on the left when viewing on the desktop to balance off the sidebar on the right. On the phone screen that doesn't appear.
However I am coming around to the view that people may be using phone-size screens 90+ percent of the time, so I think it makes sense to fine-tune for the phone screens rather than for the desktop, and in this case the difference is minor. Thanks for the suggestion!