Finally -- I snuck a picture of CC sucking her thumb! She rarely sucks her thumb when she's awake, and if she does, she stops immediately if there's something interesting (like a camera) to look at. So yesterday, when she napped late and I had to wake her up anyway so we could get to an appointment on time, I decided to take my opportunity to grab a shot of her new sleeping position.
She sleeps on her belly every time now. I always put her down on her back, and within minutes she flips over and sticks her thumb in her mouth. It's unbearably cute! At first it was tough for me to let her sleep on her belly and not flip her back over (old habits die hard). But now that she can roll over any time she wants, there's really no way I can keep her from sleeping however she prefers.