Ok so I have used my covered roaster twice now. The first time I used the kitchen spritzer with olive oil first then I made butternut squash in it. When I was cleaning it (by hand in warm soapy water), it seemed to have developed a white film on it. I used it last night and when I went to clean it this morning the same thing seems to be there as I am drying it. Just in certain spots. I didn't use the spritzer this time. Last time I soaked it for an hour and then scrubbed the film off but is this normal? Or am I doing something wrong? I typically don't wash my dinner dishes until the next morning (two young kids, crazy evenings). Ideas?