Does your baby arch forward in their sleep and make grunting noises?

While baby is sleeping, everytime she stirs, she stiffens up and pushes her head / neck forward and makes a strained face and then loudly let's out a grunt and then goes back to sleep. Or she would wake up like this but not cry. I don't see poop. I can't find anything online about this other than their back arching backwards and crying / reflux. Is this still reflux or normal active sleep?