Yeah I would say if you are close enough that you feel comfortable saying this, just tell him what you told us here. This is a difficult situation and the good thing is that your concern is only likely to make your T feel your care and concern and maybe your openness to temporary change will allow him to come out with it and say what he prefers. Then you can once and for all put it at the back of your mind and not worry about it everyday cause frankly it may seem like the elephant in the room and I wonder if your therapy sessions are really as productive as they could be.