Yes, i think they should ask. We discussed touch at my intake interview, well i asked her what her views were on touch in therapy, she said she'd always ask before touching or hugging a client. And even for clients who are ok with touch she'd check in with them if she'd touched them in session. She touched my arm once in a kind of soothing gesture and she asked me at the next session if i had been ok with it, which i was.