I had the same thing happen with one wing panel on a Goldberg Ultimate. Despite my best efforts in twisting and heating the covering I still had a very noticeable twist in one panel. I said the heck with it I'll try it first before I build a new wing. The plane lasted me 10 years that way, was the best flying plane I ever had and I have IMAC trophies on my wall to prove how well it flew. Go figure !!!!