As reference point, I'm 21 and I assume she is the same.

If I can get close to her enough, I'm asking her out: I've had a crush on this girl the near entire semester. That part isn't really "the problem" - I'm more curious if anyone has ever experienced this "phenomenon" ?

To explain, this is a girl who has paid me zero heed this entire semester. She doesn't look at me nor has ever seemed to acknowledge me. In the same way that ones eyes are usually drawn to those you find attractive - or even more so, are attracted to - hers have not gravitated to anything one-hundred feet of myself. When giving speeches in front of the class, she wouldn't even look up. Numerous times I've "tested the waters" by stealing obvious glances, but have received nothing in return: I came to assumption I was dead to her. So I moved on.

Then just this morning, I see her out on campus and she absolutely gleams when she sees me. She gives me an admiring "Heyyyyyyy", she's walking toward me, she smiles naturally. She grabs my arm and feels it while asking me about the homework - we joke, she laughs at something I never intended to be funny, and before we depart does she puts both her arms on mine once more, smoothing and feeling them over as if we've been best friends since childhood. Throughout the proceeding class did I notice her eyes rising above her taller seat-partner, their being clearly fixated on me.

I know - maybe I've come to some unbased assumption that she now "digs me". But this is a girl I've yet to even have a conversation with, nonetheless one I myself would feel so comfortable with to point that I'd put my hands on her (something she just so naturally did). How's reddit take this? Is anyone out there in a relationship where their S.O. just suddenly "clicked" and began paying attention to you? Or is something clearly going over my head?