This is very normal. I noticed my lo doing this every once in a while, though not too often. I have seen other kids do this too. If they are very little, I would say to not worry about it so much and see if it passes. If it continued to when they are a bit older, then as pp said, I would talk to them and tell them it is ok to do, but it is something that we do in private.
1/23/14 at 7:14am