The pesky problem I made for myself by not paying closer attention to the felted wool background fabric, was easily solved. The fade line disappeared with the aid of some pigment markers and the placement of my hanging sleeve. WHEW!
Although this piece doesn't appear square....it is. It's just difficult to snap a good photo when the beadwork won't allow the piece to lay flat on my design wall. I use a traditional woven fabric sleeve with a 1/4" ease, hand stitched to the backing to hang this type of quilt. This sleeve is wider to obscure any evidence of the fade line.