I'm sorry you're noticing a distancing occurring between you and T - if you've been used to a certain warmth and open interaction that must be pretty ground shifting, and I get how the fact of his seeming difference is what's causing your depression and not vice versa.

It's very easy to assume it's your perceptions that are skewed and he hasn't changed, especially if he maintains he has noticed nothing. In my experience Ts do change (for a zillion different reasons) and don't always acknowledge or even admit it. I suggest you make a real point of trying to talk to him about this, about how you're feeling and what you're seeing as changes in him. And keep talking even if he seems to refuse to validate what you're saying. If there is no change in him, then it's still valuable that you be able to work through why you perceive changes.

Hope you get some resolution next session.