Accidental Roll Over

Callie is just starting to roll. She can roll from her back to her side but that's about it. Today when she was on her tummy she rolled all the way to her back. It was clearly accidental as she scared herself with the sudden roll. I cheered hooray and clapped and she smiled and became less scared. Callie is getting strong and learning fast so I don't think it will be long before she can roll over purposefully.
Here's a bunch of photos to make up for nothing yesterday. She was asleep by 6:30 so I had about 45 min with her between work and bed.