Can you post a pic? My guess is that it is a mildew stain. I had that happen to one of my Babykicks pockets and I was never able to get it out, even with direct on the spot bleaching. I figured I killed whatever was there and continued using it with nothing ever spreading to my other diapers. However, I retired rather than sold it when DS outgrew it.
Last edited by mookie; 07-02-2012 at 03:14 PM.