Technically, I think that any time you have a copy of someone else's copyrighted work in any form, including a photograph, you need the creator's permission to do anything with it. I believe you even need permission to take the photograph! I would say, however, that entering the quilt into a show which allows photography is some sort of implied permission, though I'd like to know if anyone knows that for sure.
Most of the time it appears that copyright violators are never confronted by the creator unless it gets to the point that they are making money from the copyrighted item so more than likely no one will say anything if you post photos to the web site.
