DD has never been a big fan of tummy time but we make a point to do it every day. She was doing really well about rolling from her tummy to her back. She can consistently roll to the left and we were working on getting better at rolling to the right. But the past week she's completely stopped. She won't roll either way. She doesn't even try, she just face plants and throws a little tantrum until someone helps her roll over. I don't pick her straight up off her tummy, I help her roll over, then pick her up. Would you be concerned? At first I thought she was just being stubborn but now I worry that she may be regressing on that skill.