Recently got diverted from IAH to AUS due to weather. By the time I eventually got to IAH my connection was long gone and I was flying to a destination only served once a day. Called united, got put on the following day's flight. They saw I was previously upgraded in PZ on the flight I missed and opened up PZ on the following days flight so I could have a confirmed upgrade. That was a nice gesture given I had a 24 hr delay in Houston.