I have a fairly new set of pretty standard cooking pans (Calphalon). They are dishwasher safe. I have noticed that some of them have a small film on the bottom of them that I can't seem to get off. It looks sort of cloudy. I don't want to use anything abrasive because I don't want to scratch my pan. I'm not sure where the film is coming from. I was thinking maybe my water. I have cleaned them by scrubbing and putting in the dishwasher and I have also tried hand cleaning and drying immediately. Does anyone know what might be causing this and how I can get rid of it?