Arms raised and moving hands

My grandaughter is 6 months old, just beautiful and is doing everything early. I was wondering about the way her arms are always raised and she constantly has her little hands waving in a circular motion. I don't remember my kids doing this. She is very healthy, developing normally and doing things early. But it just seems almost as if she can't stop her little hands from waving in a circular motion. Has anyone else seen this before?