Should I chase a friend's $60 debt after seeing concert photos?

My friend posted a photo from a concert, and I opened our messages to check the $60 she'd borrowed for groceries two weeks earlier.

She had said, "I'll send it back when I'm paid on the 12th." It's now the 14th. I haven't reminded her. I don't know who bought the concert ticket or when; the photo just made it harder to believe that she'd forgotten a repayment I was still thinking about.

I can manage without the $60 this week, but I moved it out of the money I'd put aside for a birthday present. I don't want to act as though I bought permission to judge every later purchase she makes. I also don't want our friendship to depend on pretending I never lend anything I expect back.

Would you ask about the missed date directly and leave the concert out, or mention why the photo upset you? I'm torn between making this a simple reminder and admitting that it has already become something more irritating in my head.