DD is 2.8 and has done this since she was a baby. It has lessened as she gets older, but when excited she sort of shifts from one foot to the other and makes jerky circular movements with her hands, as if she is conducting a very fast orchestra 
The thing is, I used to teach children with ASD and I am hyper vigilant for any signs of it. Probably too much so; I know how ASD can present, but I have no idea how a typically developing toddler can present IYSWIM.
She has very good language skills, can generalise and (as far as I can tell) has theory of mind; it's just the flapping which worries me.
Has anyone got a child who does/did this? Should I be concerned or will she grow out of it?