I do a similar thing....but more of a hand-wringing I guess....I was told (not by me T) that it is a "self soothing" thing....I know my T notices (I eventually notice on my own) but she never says anything about it (when I notice on my own, I can usually stop)....this was awhile ago, now I tend to grab her small couch pillow when I get there and I hold it in my lap to help keep me comfortable....instead of rubbing my fingers/hands I kind of rub the corners of the pillow, I guess, when I get anxious.