OK, let me just say that Hummer Customer Assistance
ROCKS!!!!
So I called up and said I wanted to open up a case since my truck was in for a second diff failure. The lady took my info and said she'd put me on hold while she called the service manager. A couple minutes later she comes back online and tells me everything will be covered under warranty, she'll check back in with me on Monday, and they'll compensate me for the inconvenience.
She said they just want me to be completely satisfied. The whole call took less than 10 minutes.
BTW, I don't really blame the dealership. They suggested I call so we could get past the area GM rep and speed up the process. The service manager had no problem doing the work under warranty.