I was taking some shots tonight and upon looking at them at 100%, I noticed a white pixel on my black dog. Then upon further inspection, I noticed another. These shots are RAW btw. So I took a shot with the lens cap on and counted about 20 pixels across the shot that are either white, red, blue, or green. Is this normal or is this a serious problem with my sensor? Upon converting to a compressed format, they go away as expected. The camera is a 40D that I purchased used.