The featured article talks about this. It didn't go down even remotely the same way in Magnus' previous game. He also references a game which never actually happened.
He is not in charge of maintaining a chess database. Did Magnus played this before: yes. Can Hans have know about this: yes. Can he have studied this line because Magnus played it before: yes. Was the line exactly the same: no, he explained that he spent several minutes to evaluate if the transposition was possible. Very credible (contrary to Magnus insinuations)