Okay, I'm not a rabbit expert, but I know that sometimes when rabbits are scared they will play dead. And some owners are able to put their bunny in a "trance" by laying the bun on his back. But I'm not sure if your bunny was scared, and probably no one put her in a trance...

I would say not to worry, but I'm not 100% sure. Do you have a vet? Here is a list of rabbit vets by state, if you want to call. http://www.rabbit.org/care/vets.html