I am posting this quickly so I don't forget the date (since I am not good about remembering or otherwise documenting these kind of things). Samuel rolled over from his back to his tummy today for the first time. He was playing on his mat while I was doing something in the kitchen. When I turned to check on him he was on his tummy. It must have just happened before I looked since he hates his tummy and had not started to fuss yet. On January 1 he rolled from his tummy to his back two times but has not done it since.
He is sleeping pretty well even though he is sick right now. He is going 8 - 9 hours at night. I am so grateful for the rest.
ETA: He actually rolled over from back to tummy 3 - 4 more times tonight and from tummy to back once.