After returning to this thread, and spending over 18 seconds poring over the photos, I'm going to advance the theory that the wonderful Peterson bowl coating on your pipe is fighting a duel to the death with the honest cake build-up that is superimposed on it. Looks like the latter has flaked off or something, through no fault of its own. That would tick me off, and if I were you, I'd probably scrape and sand the hell out of it, and start over. Second option, send it back to wherever you got it and bitch like a wailing banshee.
I understand this correctly, you're saying that it's cake built up and cake has fallen from the supposedly burned area. I thought about this myself, just didn't want to scratch the bowl too hard just to confirm this theory.
A pipe defect is the last thing I'd advance. That's why I didn't mention it.