Well, I do pre-wash.
Happily, though, one of the other threads had a link to a website that had a link to a store about an hour away that looks like it might have my fabric in 100% cotton. I'll call in the morning and trek out there if they have it in stock. Really, I'd much rather do this right.
Oh, and to those of you who recommended Kona, this is a Kona fabric. It's actually called Schoolbus, so I expect it will be exactly the schoolbus color I need.
Thanks again to May in Jersey for posting the thread about the quilt show that is closing - and not just for this reason!