It ran well for 12 flights with no problems besides ignition.
How hard did you push it on your 5 min. ground run?

You changed environments and that can be enough to drastically change needle settings causing lean/rich running (as Mike stated). Density altitude changes with temp/humidity/altitude. I can almost bet you went lean d/t this. You did mention it was cooler.

As for BME service, I have always had OUTSTANDING dealings with Keith.

It must have been frustrating having that happen at a big event. This is not meant to be mean, but I don't understand how anyone can ask a manufacturer to cover a cooked engine d/t operator error.