For what it's worth, a friend took in a young carpet that was passed on to a rescue from a breeder that has to downsize for some reason. No RI, but for a while he would suddenly constrict very hard on whatever he was gripping, almost as if killing prey, but no food around or other feeding response signs present. That has pretty much gone away with time and handling now and we're pretty sure he had barely been handled before.
My carpet does tend to grab more tightly for a short time when I try to move him off of where he has a good grip (i.e. one hand to another while cleaning). The tight grabbing may be somewhat reflexive to him trying to keep himself in his mind safely anchored to his tree. We move more tha their cage decor, so even if we feel like we are still, they probably still feel the minor shifts of muscles and stuff beneath them.
I'm far from an expert, but I'm inclined to agree with that being related to his relative lack of handling. Since he isn't defensive or nippy, even with infrequent handling while he heals, it may start to fade away as he gets used to you even without any rigorous handling.
So glad to hear he's doing well; all his threads have been a roller coaster to follow.
Sent from my SM-G950U using Tapatalk