Andy, My Grandmother used to toss the cast iron in the fireplace every year around Christmas time to "Get the crud off and start the New Year right." Her words not mine.
I think she was following in her mothers footsteps.
While I haven't kept up the fireplace tradition I'm using those pans today and they are still going strong and as nonstick as any cast iron should be expected to be.
My oven's manual says the racks will discolor and to remove them for the clean cycle.
But I've got 3 racks and only use 2 at most so I decided to sacrifice one and have used if for the few times I wanted to strip down my cast iron. (New acquisitions or unhappy with the seasoning for some reason.)
Glad to hear your pan is getting back to normal.
You'll be happy again. But don't worry too much about cast iron. It can take a lickin' and keep on tickin'.
I don't follow the "rules" some swear by.
My pans see soap and water all the time. My Grandmother would have killed me if I didn't get the pans clean.
Acid foods like tomato sauce are cooked in them all the time and have been for decades.
IMHO all you need to do is keep them clean and dry. Maybe a touch of oil on them before storage. Cast iron only has one enemy. Rust.