I myself have found holes in foil covering acidic foods like a pot of sauce. I always assumed it was acid attack. I also switched to using the pot's lid or saran if I have no lid.

I'd like to know how much electrical energy a pan of lasagna contains and whether a discharged lasagna cell has a different flavor. Now I just need to invent a baking cell, a pan with insulated pockets so I keep my laptop and belly full ;-)