Delta has proactively contacted me — who is also monitoring this thread — and explained that, as some mentioned here, the DL desk agent erred in issuing the ticket inside the 24-hour window.

I can happily live with a mistake made in the course of trying to help someone out. Yeah, it created some confusion and a little frustration, but it was a learning experience, for sure.

I’m likewise sure the original agent feels like any of us would were we in her shoes — and probably have ourselves when we accidentally made something worse while trying to make things better.

So, with that, I’m content with my lot and don’t feel compelled to press the matter, and with their explanation I am still, overall, very satisfied with Delta.