After more contemplation, we think he just happened to learn how to pout so is consequently doing it all the time. Babies learn to smile, right? That’s a milestone. We like to think that you can learn to pout as well…because he’s been doing it ALL day off and on, regardless if he’s wearing the helmet (or not) at the time. And the pout is usually preceded and followed by smiles and/or laughter…so he’s just being a little stinker. 
I think you are absolutely right! And what kid doesn’t learn how to “play” his parents??? Just shows you how smart he really is!!!
Oh, I think he learned how to play us loooong ago!