Thank you so much, everyone! This afternoon I washed the quilt 3 times with color catchers until they came out barely colored. I suspect what happened is this: unfortunately my washing machine is one of the "low water" ones that does not have a center post -- don't get me started on that whole issue. Even when I use the bedding cycle which is the deepest water, the agitation pattern is so weird that often things will come out of the wash with huge dry spots on them. The manufacturer says the dry spots happen because the washer is so good at spinning out the water. I'm not buying it. I think when I pre-washed the red fabric there were areas that never even got wet. That explains the dye coming out when I wash the finished quilt. At this point it appears the quilt will be fine. WHEW!!
And btw, this fabric is a very good name brand. I am disappointed at how it has performed, in addition to the fact that it has a very heavy, coarse hand. I don't understand that at all.
So much for this evening's kvetch. All ended well.