Gas, Nipples, or Nudity

Magnus has started smiling recently. I don't know why babies start smiling.  Almost everyone has said, "It's probably just gas."  A bunch of nattering nabobs of negativism.  I don't believe it.  Magnus has gas, and when he does, he for sure is not happy. 

Why can't he simply smile because he is happy?  Or, when he is sleeping, smile because he is dreaming of something that makes him happy?  I have observed Magnus when he is happy, which is typically when he is either feeding or 1/2 way through a change, when he is naked to the world and happy to be just letting it all out. 

So, that's where my money is.  The smiles that pop up in the video below are so natural, I'm betting it's nipples or nudity.