Girl I used to see talking to me again?

I used to see this girl a few months ago, we hooked up occasionally and things were looking good until I stopped talking to her coz before I met her I was also talking to another girl. I stopped coz I liked this other girl more, until she left me for someone else, and that's when it was too late to go back to the other as she now has a boyfriend.
At the start of this week I was with some friends at the shops when I get a text from her saying she saw me there. I reply and we have a convo for a few days.
She admitted that she really liked me and thought I was wonderful but since I stopped talking she started a relationship with someone else. It felt a bit flirty at times as well, plus, probably an insignificant detail, but she says she was keeping a secret, when I ask what she said she couldn't tell me which I found weird
Is she just being friendly or is there some old flame being kindled?

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