T.F.
This gave me a little chuckle because I remember my daughter and her little friend I babysat doing this and giggling. They would copy each other when one of them found something new and interesting to do. It didn't last long. You have to remember everything that seems odd or inane to us is new to them. They are thinking, "WOW that looks cool when I do that!", " Or, I almost fell over but didn't.! Let me try that again because you know, repetition is good." ;-) I think you have to take the whole child, you can't say this is indicative of a particular problem but something to keep in mind incase there are other pieces to a bigger puzzle.