Like you say, hysteresis... it's the reason that use wood bow archers don't hold at full draw for ages like those compound (spits on floor) guys. Over a day's shooting it turns into string follow and will recover over a few hours unstrung or overnight.
If it doesn't recover it becomes set.
I avoid holding it on the tiller, that's why I use video.
I've had a bow explode at full draw while I held it waiting for someone who was fiddling around with the camera

(Mind it was prob' going to fail eventually, so better sooner than later)
Del