The rolling from tummy to back is a relatively new development. In fact, he more often will do it when no one is watching.
Case and point: I put him on a blanket the other morning while I went to the kitchen to get some cereal for breakfast. I walked back into the living room to find this...
That yellow bag was just too tempting, I suppose.
Colin also loves kicking his feet and eating his feet. I found him like this post-nap one morning last week. Not even footie pajamas can contain him!
I just can't get over how cute he is :)