Well, like I said, it could go either way. I see your point, I just thought they would have shown us that he was working on a comic boook before that point. In the screen shot you reference, is it of a finished comic book, or one being worked on?
All I know is, the spinning clock, on the train was the first hint that he was traveling through more time than he realized. In my mind, the comic book was the second hint, and everything was confirmed later in the episode.
It is possible that I interpreted the comic book wrong, but it did lead me to the correct conclusion at least.
