Is Aiden Reading?

While putting together a brand new puzzle that Aiden got for his birthday, we were talking about how you figure out which pieces go together (i.e. this one has blue and this one is missing some blue, so lets see if they go together).  Aiden looks at this piece (alone, not constructed in the puzzle) and says "That's part of the bus." 

I ask him how he knows that is part of the bus.  He says I don't know.  I say "Did you read bus?"  Again the response is I don't know.  Weird . . . it's an alternate universe over here as Erin told me she wanted to go potty and then peed on the potty.