I'm a prewasher; I'm not wanting to debate this issue, it's a personal choice and it's your quilt. However, even as a diligent prewasher, there have been quilts made early on and prewashing might not have been part of my repertoire. Plus there are those pesky reds that continue to bleed, even the slightest amount, after they have been washed a couple of times.
Not to fear, modern technology is at our fingertips and in our laundry room.
Grab a few of these babies and throw them in with your quilt, close the lid, say a prayer, and walk away. When you return, this is what those white sheets will now look like.
Then the next step is to see how much red bled into the creams on your red, cream and blue quilt with the cream backing. It's hard to tell when it's all wet, so toss it in the dryer for 5 - 8 minutes to take the bulk of the moisture out of your quilt, then spread it out on a floor, or in my case, the spare bed, and let it dry.
and if you are really concerned, pin a few onto areas of your quilt where there is red fabrics, (if possible) and throw in the whole box, this is definitely one of those "more is better" situations!