Why are you discussing warranty? You show me a warranty that covers brake pads and i will eat my hat. They would only ever be covered under a Maintenance contract that the oner paid for at a vastly over inflated price.
This is not an issue of warranty, it is a case of what is deemed acceptable. Selling a perfectly roadworthy vehicle, including an advisory notice in the documents which states the pads will need changing at some point is as much as the dealership is legally required to do. Wether its what i or another dealer would do is another matter