Exactly. It happens from time to time, and you got lucky. Nothing to see here, move along....

Last March, I was booked DFW-ORD-CDG, in J, on a MilesAAver award. DFW-ORD went MX, meaning I would have missed my ORD-CDG connection. I went immediately to the AC, where the AAngel rebooked me on the afternoon nonstop to CDG (the flight I wanted all along, but could never book as a saver award).

A couple mornings later, in Paris, I looked at my AAdvantage account on my iphone, and saw I had earned miles for my flight. IIRC, AAngel had moved me from a U fare to D, award to paid J. Either she didn't notice my original fare inventory, or it was easier for her to simply stick me into a paid fare. I don't know which, and don't care. I was happy to see the extra ~9k RDMs in my account.