older woman smiles at me every time she sees me. I don't know what to do about it!!!

Right first of all I'm a 26 year old lesbian (femme) and am in a 5 year relationship. I walk to work Mon-Fri and for the past 2months on a Thurs and Fri I see an attractive older woman on the street who goes out of her way to look at me then smile, I smile back of course but that's where it ends.

This woman is driving me crazy, I don't know her from 'adam' but everytime we walk past each other she will give me eye-contact then a beautiful smile, and I don't know what to do about it. I know I'm not reading into things cos the other day when I saw her I was talking and laughing on my mob and I looked at a passing car (with some fine woman in it) she saw me, looked at the passing vehicle, looked at me, put her head down and gave an awkward smile. IS SHE INTO ME??? And what should I do about it???