I'm delighted. Exactly as you predicted, Amazon shipped a new Kindle today, I have 30 days to return the old one. The response to my email said, please call Kindle Support. When I called, the guy on the phone was super helpful. He said that Amazon have a 90 day "extra" warranty in addition to the standard 1 year warranty. My guess is that it's optional depending on the problem reported.
I'm very pleased to be an Amazon customer today. :-)