babemaster, I've been in the exact situation before. There was a younger girl who I could tell was interested in me (prolonged staring, and I mean long. All her friends would turn and look at me at once when I walked by, blushing when I smiled at her, and finally rubbing up against me in the halls to try and get my attention)
Well anyway I caught on to this rather quick, I started giving her a little more attention and she started avoiding me, so what did I do? I backed off. Now she's always trying to get my attention again, but I've been too busy with other chicks to try and hook up with her agian.
My advice is to just pretend not to even notice her for about a week and see if anything changes.
Good Luck.