My son did that I just left him
My daughter is almost 2 and still does this. I heard a saying the other day which was “you can’t make a happy baby happier” and I love it. If she’s uncomfortable she will move. My daughter also gets little finger marks on her face as she sleeps on her hands too.
Yeah, mine still does that at 17 months. A lot of them seem to. I think it's a comfort thing. It's like a fetal position and the pressure on their face / front side is comforting, like in the womb.