That type of wear is pretty common for me. I think all, but my newest pair of waders, has that same kind of seam wear......and no, I don't have tree trunk legs.
Sort of makes sense that it's wearing along the edge of the inside patch, because it's thicker, and maybe stiffer there. It might be causing that repair edge to raise, and have more contact. FWIW, none of my similar wear spots are leaking. If they do, I'll just put a ribbon of Aquaseal along it. I do have some wader material included in patch kits, that I could use as an extra measure of insurance.
I like Aquaseal for repairs. Out of the different adhesives, Aquaseal seems to adhere well, and last the longest. Never tried Pliobond, but I do have a couple bottles of it. That might be the way to go, if you use a patch. Barge Cement is something used to glue on wading boot soles. That might work too. Shoe Goo too.
briansII