My daughter used to do this. It turns out it was a sensory issue. She has mild autism (PDD actually).
One thing you can try is to give her a massage before putting her into her pajamas. Put a little lotion on your hand and rub it into her arms. I like to sing "Rub rub rub the arms and rub rub rub the arms and rub rub rub the arms and this is how we rub the arms" as I do it. I start with one arm, then her hand, then the other arm, then that hand, then the legs followed by the feet. Then I do her belly/chest, back, and gently I do the face. Your really just rubbing the lotion into her skin. But it helps with sensory issues and will help her calm down for bed too. My daughter LOVES this.
I don't think it's Trich like the others here have suggested. That's more something that happens in those who are older. With babies and toddlers such things are usually a sensory issue. Still, her ped would know better.
at 6:31 PM on Jun. 24, 2008