According to the rules of the board all fabric is supposed to be washed :
5. When an activity includes swapping fabrics, they should be washed, dried and ironed and cut as precisely as your skills allow. Oranizers should not require they be starched or otherwise treated unless it's essential to success in the type of project involved. Those of us who don't normally prewash should make exceptions when joining in group activities. It's a courtesy to others who may have allergies or other health needs requiring smoke and animal free environments/supplies.
here are all the rules for the swaps :
http://www.quiltingboard.com/t-20154-1.htm