I think it is something to do with the cushion not the fabric because some of our BB sofa chairs/at the showroom also start the same pattern of "moldy looking" will send you pictures. I think it is the down/feather materials that causes the decolorization on the fabric..
In the meantime, I would ask BB to send us the new insert (seat cushion) together with the new fabric, have them shipped by air as well.
thank you ka.