I had a subconjunctival hematoma, now fading and see what looks like a pinguecula where it appears the source of the bleeding began. is this unlikely?

Unlikely: Pinguecula are poorly vascularized and would take considerable focal trauma to bleed. You are looking at the resudual blood as the rest is absorbed. That tends to localize around the edge of the cornea which may give the false impression that this was the bleeding source. Spontaneous hemorrhage of the conjunctiva usually occurs farther out from the cornea.Most are benign and no problem.