Well, apparently, shortly after I left, she cried. She put her coat and backpack back on and wouldn't take them off. I guess she felt comforted in that, as long as she had them on, she wouldn't be staying. "Circle Time" is the last thing they do before getting picked up, and she stopped crying during Circle Time and started joining in.
Despite this, when I asked her if she had fun, she said, "Yes," and when I asked her if she was looking forward to going to Playskool again, she said, "Yes."