Oh yes, though Professer Xavier remained congenial he was only human, and so the tiny tells of someone suppressing a worried reaction were still there. It would have been strange indeed for Moriarty to have missed them considering that he was watching so intently for exactly that reaction.

[So he was recognized, then. Time to back off. This was an example of the most difficult kind of distrust to overcome, the kind smothered by thick blankets of trying to give someone else the benefit of the doubt but never quite believing it. It could have been far worse, of course. Ultimately, all Moriarty really needed was a harmonious professional interaction. With an outwardly friendly response like that, the outcome was all but assured as Moriarty proved himself over time.]

"I have no doubt that you would be a fine teacher of a wide range of subject matter. Pleased to meet you! We'll no doubt run into each other again sometime."

With that he gave the man a carefully charming smile and turned to go.