Why would she do this all of a sudden? She hasn't done that before.
Is this a way to gauge interest?
Is this flirting?
Context:
I find a girl that I've known for 2 months by now, she has looked at me from a distance (and while I'm not looking), stands close to me (proximity) while all areas are wider than 6 feet (she stands less than 1 foot of distance) even while we're walking together (to the point that I touched her thighs multiple times unintentionally but she didn't mind). She's ok with hugging, even to the point that she stays a few seconds longer (which I don't mind) and she broke the touch barrier first.
So I haven't seen her in a while, we find each other and we hug each other (as far as I've seen, I'm the only one who hugs her like this). Usually, it's a side hug type of thing but as we finish the conversation (due to some errands to finish) I give her a hug, while I did that, I noticed that she suddenly hugged in front (instead of the side hug). As this happens, she holds me kind of tight and lifts her knee towards me, pressing my groin area and there wasn't anything nor anyone around us to provoke this type of movement. It lasted 3 seconds and then she stopped and we finished hugging and we say our goodbyes.
I've never seen a girl made this type of move nor I know why, she's comfortable with me all the time.
