My DH the amateur herpetologist says maybe he's trying to establish dominance over all the other babies....
(Some male lizards do that, bob their heads at other males. LOL)
Seriously, I agree, it sounds like he's getting to know his body. He might also be experimenting with his vision. Is he looking at anything when he does this, even the floor? Might be practicing focusing his eyes. If he's not up on his hands and knees when he does it but just on his tummy, he might be too close to the floor to focus properly - just a thought,