Body language. hhuummmmmmm... I noticed her mirroring some times. Sitting up when she is interested and sitting back staring out the window when I am not on the subject I should be on. Not much else I can think off. O and I had to say sorry a few times a year ago to her as she caught me staring at her legs. She said nothing at all about that. I half thought she might be annoyed or something.
So thats it... how they sit on their chairs!