I don't think it would bother me but everyone is different. I am becoming a T and take meds and go to therapy, but I wouldn't offer up this info for this very reason. Some people might feel like the T can relate to them, others might be concerned.

T's are just people and and many if not most of them do choose the field because of some personal experience with it. I do think it's odd that he shared this info with you in a phone interview before you even saw him, and without you asking. But that might just be his style and a way to weed out clients that would have an issue with it. I don't see it as an issue in of itself. I think it shows a lot about his personality type, so it might help you judge if you think he is a good fit or not.