Was he sitting the last time you looked at him? Did he know you had a headache? Did you feel it was out of line for him to be standing looking at you or looking out the window at you? If it made you feel uncomfortable then tell him that it made you uncomfortable, tell him it made you feel creeped out. See what his response is.
A therapist should be able to handle this kind of situation without getting defensive.

Have you ever talked with T about comfort levels as in space between the 2 of you?

Just some thoughts. Maybe you're picking up on something or maybe not.