I think this quilt is beautiful. Would you share the name of your longarmer?
I'm afraid the shadow may well cost you a ribbon, and that's a tragedy. I know if you enter a large show they will spot that right off. You know how they are about even a stray thread that shows through.
Don't be disheartened though. This quilt looks like an heirloom to me.
'Just a thought...have you thought about just naming the quilt something like "Faint Blue Line"? Imply that you intended for it to be there!