Ever since my daughter can toss &I turn she's been doing it in her sleep ever since now she's 2. I'm sure it's fine he's just trying to get comfy.

Does it wake him up or keep him from staying asleep? One of my twins used to bounce her head up and down for 10 minutes each night (a sensory seeking activity) before she would fully settle into sleep. But it didn't seem to be bothersome, quite the opposite, it was soothing. She eventually outgrew it.