I'm LoL'n at the comments.
Very evident that the 'majority' of comments are from younger, un married guys.
Here's my take - older, married guy.....
Flip a coin.
She's 'supposedly' giving you the proverbial eye.....you're there like a love struck deer....skat or get off the pot. Ask her if she wants to hang out some time....or let it go.
Life is too short for games. The 'hit and run' technique works VERY well with chicks you don't see every day.....but you WORK with this one, so you'll see her all the time.
FYI - I was 'hit and run' with this chick I worked with back in the day. I was cheating on my g/f with her. This chick found out. I had left my g/f for her. We started hanging....
This past April we've been married 13 years.
So you either got what it takes together or you don't. In between is just memories.
PERSONALLY - since you work with her....I'd let it pass....unless she really comes on to you and she mentions she's single.....otherwise, you're creating a difficult work situation.