It could be. Other characters in the book could tell this person that he's suffering from the Mandela Effect. I think that has to do with someone erroneously remembering that Nelson Mandela was in prison.(official history says he wasn't.)

The conspiracy theorists out there say that the people who "remember" alternate events like this are doing so because the timeline has been changed.

Actually, that might be cool in a lot of different books. Good question!