Weird popping bubbles under incisions. Is that normal?

You must be seen by your doctor.  The popping ay be just the sutures.  However, if it is something more significant, the implant is directly under that wound.  

There are several things that can give the symptoms you describe, none of them abnormal. It is likely the implant your feeling, possible some folds that come and go. It could be soft tissue that folds over the implant in different ways. If it were earlier post op I it can be pockets of air or fluid, both of which resolve. Best course of action is to ask you surgeon to exam that specifically at you next visit. Hope this helps