Reddened area above navel, along muslce repair line

I'm about 7.5 weeks post op now from a TT with muscle repair, and my recovery had been going very well.  At my last post op appointment, the PS noticed a hardened area above my navel, along my muscle repair line and suggested I massage it.  The day after I saw him, the skin overlaying this hardened area had turned red and was quite sore.  I waited two days before calling him in case it was just irritated from him messing with it during my appointment.  He suggested a possible infection and now has me on antibiotics.  I've searched the internet, but haven't found a case similar to this.  Has anyone else experienced something like this?  My incision line looks great, it's just this strange red spot (about 1.5 in by 1.5 in) along the musle line.  Could this be a simple popped stitch, or am I looking at a seroma or hematoma?  Eager for the recovery period to be over by now.