He Rolled Over!

Out of nowhere, Ian rolled over! I remember Eli would work so hard just to get half way there and just not be able to get ALL of the way. Well, Ian has not been showing any signs of trying to roll over, but what did he do today....flipped his butt right over! When we do tummy time he has been trying to get "up" and scooting around, but no signs of rolling over. I wonder if it is just a fluke?