I hate to be the bearer of bad news........but how close to overheating did it get to.

The reason I ask is because the hottest a engine will get is after the engine is turned off, and there's no more coolant flow (heatsoak). If it was right at the point of overheating, it probably got REALLY hot after you turned it off.

It should be a dealer repair under warranty, and I'd insist that they checked the engine over really good for any further damage.