My marriage counselor seems to do that at times, sit how I'm sitting, whether it's crossing his legs the way I am, holding his hands a certain way (never noticed him playing with his hair like me though!) He's shared before how he was taught that sitting in a particular way, combined with what he's saying, can be "hugging from across the room." So I'm pretty sure he knows that copying gestures, which I think is called "mirroring," can make someone feel more in sync/connected. (I've read before that it can also be an effective technique if you're flirting with someone, incidentally.) I haven't noticed my T doing it though.

On another note, at one point, I was interviewing for a job, and MC gave me a few tips. One was to hold something, like a pen, in your hand to keep you from moving your hands too much as you talk and to help with feeling anxious. Since then, I've noticed he's generally holding something in his hand during session, whether a pen (he doesn't take notes) or coffee cup/other drink. Or he'll have his hands clenched tightly in fists. I know he has some anxiety issues, too, so it might partly be that. Maybe combined with his being from an area of the country where people tend to talk with their hands, so he's trying to avoid that.