What does her stroking her glass mean?

I thought I read or heard somewhere that a subtle sign that a girl is interested in you is when she plays with certain objects in your presence. For instance, I recently chatted with an ex girlfriend of mine and whiled we chatted she kept stroking her glass of water up and down. What does that mean? Does it mean anything lol?
Updates
+1 y
I'm familiar with the whole handjob thing, and while I would very much like for that to be the case in this situation, I'm doubtful. I'm still very much in love with this girl and want her back desperately so my ability to see things unbiased is strained.
What does her stroking her glass mean?
Post Opinion