My 5 month old decided to roll from back to belly last night for the first time in his sleep. He hasn’t done it awake yet. I was kind of excited because I have thought for awhile that he’d sleep better on his belly. Well... he got to his belly and then all he would do is hold his head up like he does for tummy time during the day. He wouldn’t lay his head down and relax, so he started crying and I had to go in and roll him back over (even though he knows how to roll to his back). Any advice? I don’t know why he instantly lifts his head up and won’t relax