I don't pre-wash and I don't worry. The finished quilt gets washed so anything that was in it is washed out at that time. I have washed some yardage that came from an estate sale that smelled musty but that's about it. I've never had any problems with shrinkage or bleeding.
I've learned that I have a different vocabulary than some in this thread however. To me pre-cuts were layer cakes, jelly rolls etc. I never considered a fat quarter a pre-cut. Learned something new.