tti's turned gray?

put a set of tti's on my 340 last summer and done ok, last fall made 1 nos pass and after that the polished,ceramic coated, thermal barrier, Mucho $ headers turned to a gray haze about an inch or two past the flange anyone else had this trouble? oh yeah and looked the other day and guess what the flanges and right past them on a few tubes, spots of rust are showing, they say if the car sits a while to oil them but I start it and let it heat up about every 3-4 weeks to avoid this prob during winter, anyone got any answers or similar probs?