Struggling to think what is right in this situation?

I caught a girl staring at me while I was working at a big event in the city , her and her mum are big fans of the band I was there backstage with. The daughter kept staring so I later found out who she was and added her online, I asked for her number and she said she would like to “TALK” then said she has a boyfriend but asked me very general / casual questions an seemed to want to get to know me.

I think because of my relationship with the band, perhaps she didn’t want to refuse the opportunity to talk with me as a friend?? I told her I want to get to know her but I am going to give her space since she has a boyfriend and that she should text me when she wants to talk.

Lets say theoretically one day I’m still single and she messages me saying they’ve broken up and I don’t hear from her until then, is this still a major red flag?

We haven’t really flirted but she knows my intentions were to ask her on a date until she advised me she was taken. We only texted back and forth one or two times once I found out.