Might be her brother, Uncle, Friends Boyfriend, you don't know. I have met someone through work, i did nothing and hated myself for it. All i can suggest is trust your gut instinct, if she makes you go all gaga like a baby inside and she smiles when ever she seen you, go for it! Come to think of it, there are two girls at my current workplace that i like, but i do not love them or have the same feeling as i did towards the other girl, just make sure you like them for the right reasons.
The right reasons, Personality, Eyes and how they make you feel. All other visual things can be deceiving, i once knew a girl that i thought was the most stunning girl i had ever met, i talked with her and she turned out to be a complete snob and was flirty with all the other guys.
I think base line you should find out if she is single first, talk about guys you see her with, this way you get to find out if she is already taken and sometimes find out how she likes to be treated, from this you can suggest meeting up for a coffee or a hot chocolate depending on what she drinks to continue your conversation.
Don't worry about what you will say while your drinking your hot chocolate/coffee, just don't drink it so fast that you burn yourself or make it seem as if your rushing to get away, relax n blabber on about anything (dont talk about ex girlfriends) if you feel the urge to talk about one of your ex's refer to them as a friends current girlfriend and tell her that your friend is stupid for being with her, this ensures you are a decent guy and are looking for the same sort of relationship as she is.
Dont come on too strong! i have screwed a lot of relationships up by thinking THEY ARE THE ONE AND ONLY, blasting my way into trying to start a relationship, this causes so many problems its just not worth it. go with the flow.
I am not happily married but i guess i have had my fair share of girlfriends to know what love is and what lust is.
Your eyes can sometimes decieve you, don't fall for someone until you get to know what they are really like.
Hmm i think i have definately said too much, i do wish you all the best in bumping into her again and if you do just openly talk about how you felt when you first seen her, trust me it will either end in happyness or resolution, either way you are able to either can her from your prospective so you can move on with your life, or open a gateway to a whole new world of plus one.
Good luck!