Originally Posted by EssamHelmy
.... The foil isn't burning. The "burn holes" you see are the molasses attached to the foil and it leaves a residue when it burns. Its not the foil that is burning, its whats attached to the foil that was burning.
I'm betting he is seeing it on the top of his foil, and therefore it wouldn't/shouldn't be residue up there. I see this occasionally too, haven't worried to much yet.