This bump was there all the time since you had the procedure? On later checkups, did any of the doctors mention that you need to rest until this type of incision heels, with special warnings for heavy weight lifting and intense activities. So, since i had my fair share of incisions, I can say that neither of them had any hard under-skin bumps so long after the procedure. That's why I think you should at least call up your doctor and ask is this something normal and what, or is there a reason for you to be concerned. But except this, incision look OK? And is there any pain or warmness around the incision area?