My ds is 9 months old, and has recently started doing a strange thing. He lies on his tummy and kind of lifts his bottom then pushes his pelvis down into the carpet IYSWIM. Whilst doing this his head is on one side and he has a far-away expression on his face. I can only think that he has (ahem) discovered that his willy can make him feel nice. The thing is, he does seem to be doing it rather a lot. My question is - should I stop him doing it? Does anyone else's baby do a similar thing? Please help - I'm finding it slightly worrying, thanks.