Should I add or message?

I work in a nail shop and this other chick came in yesterday, and another person did her nails. I was busy doing somebody else at the next table, and I could totally be wrong about this, but she looked my way a couple of times and maybe she was vibing me maybe not, I never had the chance to actually talk to her. I found her profile on FB through mutual friends, Should I add her or message her first? I'm thinking about opening with if i do message her:

Hi, were you in so and so yesterday? I wanted to talk to you, but never got the chance to.

It'd be better to wait until she comes back and talk to her in person so you don't have to dig yourself out of the "internet creeper" hole, unless you're certain she was vibing you.

If you work in a nail salon, she'll probably have made the assumption you were gay unless she directly interacted with you. No offense- I work in a women's shoe store and it comes with the territory. Hold off until she comes back, and if she doesn't, then you work at a business that involves being surrounded by women at all times so it's not the end of the world.