Oh, Mamagrande, I'm feeling for you right now. Had something similar happen and like you I couldn't allow it to go out of my studio for a customer. Took HOURS to unsew, but well worth it.
Just finished my own whole cloth and showing my husband I realized I had a tiny pleat on the back--think it was from rolling it back and forth several times due to thread colors and circular designs. Even though I know it will mean no ribbons, etc in the show I'm putting it in, I really don't care---first competitive show for me and I've been thinking about it for 2 yrs and just decided I had to do it--and besides I LOVE the design and that's what's important--plus getting feedback from judges (like, no pleats!)
Hope the quilt your are working on makes lots of $$ for the charity!