I would assume Dr D would back me up on this:
Wear items under the new car warranty, such as brakes, wipers, bulbs, etc usually have a 12 month/12,000 mile special warranty coverage. It should take care of the brake pads if you are within those limits, and the dealer isn't claiming "vehicle abuse", (and if they are, I'd ask how they are coming to that conclusion). Your word against theirs, and you say the tires look good. You should be covered, but you really need an answer to why this happened to begin with. They are NOT obligated to replace them again in 10,000, just ONCE.

Gilly