The regression because of a new baby has, as one of its underlying causes, a child's sense of being deprived of her parents' attention.Your traveling could have much the same effect, from her point of view, so there is definitely a possibility that your being away is a factor.
It's just as likely that getting out of her usual routine, having a distractingly great time, etc., has also contributed.
Assuming that your daughter communicates well and doesn't have any complicating issues like attention deficit disorder, I would suggest your checking out the book How to Talk So Kids Will Listen, and Listen So Kids Will Talk.
There are very few parenting issues that can't be addressed effectively. (You can read part of this practical guide to communicating with kids here: http://www.amazon.com/How-Talk-Kids-Will-Listen/dp/038081...) The authors demonstrate exactly how to help children communicate, identify their own emotional issues, and participate in finding workable solutions. Good luck. I've had very good results using this approach with my 4yo grandboy.