Mission Control glitch in Lion

The three-finger swipe to invoke Mission Control is great. I believe what I’m supposed to be seeing is a layout of the open windows on my current desktop lying clearly below the miniatures of the Dashboard and the four desktops I’m working with across the top. This is the way it works almost all of the time, but sometimes a Finder window will show too high on the screen, partially covering up one or more of the miniature desktops at the top. This certainly must be unintended on Apple’s part. Is there an easy way to report this (or is it likely they already know)?
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Joh Russell