There is a coffee shop that I go to regularly, and one really cute girl has always been a little flirty with me. In the beginning, she was always trying to make herself noticed, approaching the areas that I was even when they're out of her way, and becoming more animated when doing that. I eventually introduced myself and she's always gone out of the way to make herself noticed/available to talk to, and is pretty flirty.

The other day (two days in a row), I brought my ex-gf to this coffee shop, and both times she uncharacteristically shied away. Then she made a comment about "my girlfriend." I didn't correct her then, but I came back another time and asked why she assumed the girl I brought in was my gf. She asked if she was wrong and I said "yea, she's my ex that I still try to be friendly with." She actually looked relieved, and became flirty (but not overtly flirty) again.

Does anyone have any tips on approaching to date/hang out with? The being at work thing seems awkward to me?