Wondering if this girl is checking me out

[AWill718]

I work in a store and I only been working there for a month and a few weeks. From the time i started working there i spotted a girl that work as a cashier in the store. Really tall and gorgeous. Asked a few people about her in the store and I get the same response that this girl has a bad attitude and guys have approached her but she always shoots them down. So now a lot of the guys don't pay her any attention. Since I have been there i haven't said anything to her or even really looked in her direction. I walk by the front end a lot and it seems or every time we happen to walk by each other i always see her looking at me. I always catch out the corner of my eye that she somehow is looking at me. One time im walking down the aisle with my friend who is a female and she was walking towards us and she moves to the other side of the aisle and as she walks by us she flips her hair. There is a lot more to this so bare with me lol. I told another guy in my department that i thought she was cute. He happens to be a really close friend of hers. A few days later he keeps joking with me saying "there goes your girlfriend" or "there goes your girl". Him and this girl knows each other and even though about becoming room mates with each other. Why would he even say thats my girl and all that? Does he know something i obviously don't? And since I'm not going out of my way to say anything to her unlike every other guy thats walked through the store is she checking me out wondering why im not giving her attention or does she think im attractive?