So hey, no, not tendon. Internal suture - supposed to dissolve over the course of the next eighteen months.
Picking at it too long would be a bad idea because it's attached to delicate internal bits. I've subsequently had the outer part cut with ultra-sterile scissors by an emergency doctor, and the remaining thread slipped back inside and the hole has healed.
I know from when the doctor was testing it and tugging on it that pulling on it hard enough caused OH GOD OW.