Putting lipstick in front of me?

I was at this coffee shop hanging out with my brother at night and i had a cool conversation with the cashier and i couldnt really tell if she was interested in me. So while i sitting down talking to my brother i seen that she was staring at me. Before leaving i seen her putting lipstick on while looking at me.

Is this something most women just do normally, or is she teasing me?
Putting lipstick in front of me?
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