Did he admit he forgot your name, or is this your interpretation? Did you ask him what his look meant? Is it possible you entered his office in a way that startled him or caused him to give a certain look? I just think it's unlikely at the beginning of session when he likely looked at his schedule to see who was on his schedule.

I thought you meant he tried to say your name in the middle of a sentence or something. But I've found I'm wrong about some of my T's "looks," so much so that now I just say when he has a look, "what's that look about??"