concerned...

Kari
Jaiden used to be able to roll from his tummy to back. He didn't do it all the time but he did it kind of often. 
Now he is rolling from his back to his tummy. And he's doing it all the time, even in his sleep. But I'm worried because now that he's doing that he has completely stopped rolling from his tummy to his back. 
It worries me because in the middle of the night when he rolls on his tummy he will wake up screaming and I have to go in his room and turn him back over on his back. 
Is this normal for babies to do? Once they start rolling the other way they kind of forget how to roll the other way?