Would this be creepy for me to do?

so there is this girl at my job (i work for a big aerospace Company) and i see her every once and a while and every time we walk by each other we smile and give each other a stare. well i wanna ask this girl out, the only problem i have is that i never no when i will see her at work sometimes i see her and sometimes i go weeks or months without seeing her. I did find her face book (i didn't go looking for it so don't think i'm stalking her or anything) would it be creep y of me to message her and try to break the ice? She works in my building but i dunno where, so i have no way of seeing her on a consistent basis