There is a black, sooty like, film that suddenly appears, every once in a while, on my white plastic toilet seat. It does not come on any other surface in the bathroom.. only on the toilet seat and lid. It also does not come anywhere else in the house. I have radiant heat (so no air ducts at all) and my furnace is gas fired. Does anyone know what the heck that is? It wipes off fairly easily but is quite a nuisance.
