Ah, the old "to wash or not to wash" debate.
I wash it just to be safe.
1. Bleedage. At least once a week someone on here posts of how they washed a quilt they had finished and the darks bled into their lights because they didn't prewash. And why spend the extra money buying those color catchers when you can just wash your fabric and get the extra dye out to start with?
2. Shrinkage. 'Cause I'd rather not have the puckers later.
3. Not really knowing what your fabric has been treated with, where its been before you bought it, and who has come in contact with it.