Be careful about saying “no moisture”. Think about relative moisture readings, not absolute readings. Look for a difference between your suspect area and surrounding areas of the same material. This is particularly important with cheaper moisture meters (that looks a lot like a General Tools one I had) which are marginally precise at best.
So if an area of drywall below a poorly flashed window reads 25, and the drywall a foot or two to the sides of the window reads 5, the window is likely leaking.
Taking one single reading in one spot is pretty much useless, you need that control measurement to go with it. If you aren’t already, think about upgrading to a higher end moisture meter. They can be worth their weight in gold and help keep you out of trouble. A $400 moisture meter is a much better investment than just about any other inspection toy, I mean tool 