DH says the stain is able to grow because it's organic, and you can stop it from growing with oxiclean and it could take it out as well. My hesitation with that is that stuff really likes hot water, but quilts not so much... He also says if you try the vinegar it wont "set" the stain. So it would be okay to try it first and then try something else, as it wouldn't make the stains any harder to get out.
Oh it's only in the first photo, if someone is looking for it. Truly a beautiful quilt. Sure would be nice for it to be clean. :)