Wayne, if i am correct in what I see from your pic & your describing it, it is the rear part of the fuse. top that is not flush with the top edge of the fuse sides, correct? If so then I would not worry about it. This section will be behind the "backrest" that sits on top of the fuse top & it will also be covered when you put the upper turtle deck sides on the top of the fuse sides. so the uneven surface will not affect anything at all & will be hidden from veiw. The build looks great so far. I am just finishing up the wing on mine & have the tail feathers built & will be starting fuse. tomorrow. Bill