New answers tagged grilling
It might be rust, but if it was rather smooth and more orange-ish, it might've been that you ended up seasoning the metal. (seasoning over shiny / polished metal tends to be orange until you have a few coats down when it'll get darker). Of course, as you mentioned that you were able to clean it, it's more likely it's rust (as Sean Hart said), as seasoning ...
It is most likely rust. The covers over top of the burners will eventually experience that sort of decay. They have a constant barrage of high heat applied to them, which speeds oxidation of the metal. You will experience this effect with the burners as well.
I don't know whether they banded it or you just don't see it anymore but they do have charcoal seasoning maybe at a health food store.
Top 50 recent answers are included