I have noticed that if I've treated Xs well - no matter what the reason for the split up - they occasionally come cycling back thru to at least take a gander at you again. The caution is that, yes, they are remembering the positives of the sitch again, and wondering if your behavior and changes are real, but but their choice to cycle back has more to due with discontent in their current sitch.
DB principles apply here as well. Familiarize yourself with the DB/DR texts and proceed with light, positive caution. : )
