Rolling around and growing up

Last Wednesday was an eventful day for Zoe. She demonstrated that she can easily roll from back to front when she chooses. Previously she was only rolling from front to back. We think that she had rolled from back to front a few times before but no one had seen her do it. She still seems a bit unclear about why she should want to roll over; after all if she wants to get somewhere she can probably get one of us to take her. However she's starting to think that it might be nice to explore a bit.
Last Friday Zoe turned four months old. She continues to grow and is doing great.