I don't think so. I worked for a fabric manufacturer for several years and we
never produced fabric as you mentioned. We aimed for the best quality but
there are always a few rolls that won't make the A grade.
Fabric is usually sorted out by the number of defects. AA grade, A grade, etc.
But it is still useable. You might have more slubs in the B grade or misprint
on one side that kind of thing.
As to why you are paying these cheaper prices it could be overstock or they
buy fabric from stores that went out of business. Enjoy! :D

Am I allowed to name the store?

My guess would be 1st printings on lesser greige goods. We had a store like that here. I was so sad when they closed.