Both of the T's I have seen were about the same age, which is about the same age as I am. They both have been practicing for 25 years or more. I don't think I would be comfortable with anyone too much younger than me, no more than 10 yrs younger, I think. I don't know, I just think it would be weird.
My last Psychiatrist was fresh out of school by a couple of years. I found that a bit awkward, and hard to relate. Since I quit taking meds I no longer see her.