Valve adjustment on Honda Pilot

I brought my pilot into the dealer because the engine light displayed: VTM-4. They charged me $750 for a valve-job but when I brought it home the problem occured again with the same engine light display. This happened 3 times because they couldn’t figure out why the valves kept needing to be worked. By the way, the car only has 45k miles on it. The third time they discovered the head-gasket was blown and the head was cracked. Honda replaced both and this was covered under the extended warranty. When I questioned Honda about the valve issue, they tell me it is a seperate issue and not covered under the warranty. Does that sound kosher? I really would like the original $750 back. What do you think?

The valves on a pilot should never need any work. Was the engine overheated at any point in its’ life? My Odyssey (same engine) has 126,000 miles on it and the valves are fine.