There could be some.... maybe... but good luck with that! Sorry, I couldn't resist. You can take the girl out of DC, but can't take 34 yrs in DC out of the girl. Ok...having made my little joke, G St Fabrics is in Rockville Maryland and is definitely the motherload and worth a visit. They have stores in Falls Church and Centreville, VA, but they are smaller stores.
http://www.gstreetfabrics.com/about.shtml. They have a photo tour here and instructions for getting there via the metro.
http://www.gstreetfabrics.com/locations.shtml#
(Mary Jo's in Gastonia NC is my 'little G St' and saves a trip to DC.)