u/Apprehensive-Bug5752

Last night I made cornbread in a cast iron skillet. Covered it with aluminum foil after we were done eating and it was pretty much completely cooled. Just got home from work, went to get a piece of cornbread and it almost looks like the aluminum foil “melted”? onto my cornbread??? All of the little grey/metallic spots on the cornbread perfectly match up with the holes in the foil. It was also covered by a second layer of aluminum foil bc a single piece wasn’t wide enough to cover the entire skillet, the holes are only in spots that were covered by the second layer so I know that there’s no way something hot got onto it, the holes weren’t through both layers. Can someone please tell me what the hell happened?