A user on reddit, dadnaya, made a post on May 27th, claiming that something was very... off, about what would happen when you play him. They said, "As for the new patch, Reinhardt's hammer will register a hit only after the full swing. Before the update while the hammer was in the middle of the screen the hit was registered."
But! To our relief, Bill Warnecke of the Blizzard team commented on the post saying this was accidental, and that they didn't intend to change his hammer. He is now looking into this and will most likely update us when it has become "fixed".