Welcome to the gang! Your quilt is beautiful. I rarely prewash, but one thing I've learned about using bright fabrics is to cut off a small piece, lay it on paper and draw around it, or measure carefully, then just hand wash that piece in the sink with hot water. If it runs or turns water a color, I know I need to prewash. Then I dry it and lay it on the drawing to see if it has shrunk or not. Better safe than sorry when it comes to bleeding dyes.