One of the places Henry found while exploring was the gym. He had lots of things on his own mind but they vanished once he realised who was in the gym with him. He didn't have to have his comic books with him to know that he was Captain America.

Staying by the door, since Steve seemed very busy, he just watched in awe of the fact that his ship might have actually done something brilliant instead of all the other crap it's pulled so far.