Oh my God, this can't be real, can it? Temperature spikes and you keep driving 45 minutes because the engine was running fine and was cold to the touch?!?!?!? Plain and simple, you burned it up man, holy cow!
The engine was cool to the touch because it's aluminum and didn't have any water flowing through it to extract the heat away from the cylinders. The engine fire was most likely engine oil spurting out from the warped heads running with no water in them.
If I were you, I'd keep the temp needle and driving 45 minutes thing quiet or you'll be paying for a new engine, fire or no fire, provided your insurance person knows anything about engines. That's negligence if I ever heard it and not covered by warranty or insurance.
