My kitten does the same thing sometimes. I think he is just really excited about eating his dinner that he gets over excited. I wouldn't stress but if you are really worried maybe a vet check up is in order.
I have bred a few kittens that have done this.
I don't know why it happens but don't worry, I'm sure she will grow out of it.
I have had that happen to one of my kittens too. I noticed it when started bottle feeding him when his mum didn't have enough milk. After he started eating solids, it happened right after he ate a full meat-meal. I would put him to my chest under my clothes or if I had to leave, put him on a kittensafe heatpad and covered him up with a blanket. It just stopped at about 6/7 months of age. He still lives with me and still loves to pur underneath my sweaters...
I guess it's just of matter of using up the necessary energy to digest the food, which deprives the body of the energy needed to keep warm. He was quite bald. Is your kitten too?