Yes, I think a T should ask, if a client hasn't brought it up first. I specifically told my T that I was uncomfortable with touch and she's never initiated anything beyond the handshake the first time we met. The only time she has my permission to touch without asking first is if I'm in such a panic that I'm non-responsive. In that case, she can touch my arm or hand as a means of grounding me. I've made her aware of this after a session in which I was panicking so badly that I was nearly non-responsive.