Unfortunately, I don't know when it happened. I noticed the first exterior crack about a year ago, and the first firebox crack maybe a year before that. But since it wasn't terminal damage, I put off dealing with it. Today when I took pictures for the dealer I noticed 3 more cracks, and the way they all join underneath. It's bananas, all right!
I have done high-temp runs before, for sure, but hasn't everyone?