I experienced that recently too --- almost 10%! It turned my king sized top into a queen size! I wasn't happy at all, BUT..... the finished quilt was absolutely gorgeous. I purchased the top from a friend who had pieced it out of "thrifty" fabrics that were not pre-washed, and I also used Warm and Natural batting. I was thinking that it came from her not pre-washing the fabrics, because I use W&N almost exclusively, and have never had this kind of shrinkage before. I'd be willing to add extra borders to future quilts if you think this may occur again, but in my opinion the W&N batting is wonderful over the long term. BTW, your quilt looks wonderful! :D