I made my first quilt this week from my fabric stash (I make children's clothing). All that fabric had been prewashed. I'm about to start on my second quilt and want to use a jelly roll for part of it. I've always prewashed fabric when I made clothing. I'm a bit hesitant to wash this jelly roll b/c I don't want to lose 1/4 inch of it in the wash due to straggly threads. Is it necessary to prewash fabric for quilting?