I think that 60 votes of positive feedback speaks for itself. I think it'd be a much different situation of you had a feed back of 2, and one of them was negative.
You've been an active member since you started with the group in 2003 and this is the only negative feedback? - again that says WAAAAY more than one retaliatory comment from one seller.
This is how I look at it - When I see that someone has one negative vote in a long string of positive votes I check the original For Sale thread to see what went wrong. In this case it's clear that you felt there was a problem with the original item and the buyer (you) tried to resolve the issue before leaving feedback. After a suitable amount of time without resolution - you had to resort to telling it like it was in your user feedback. When I see something like this I just write off the negative feedback as retaliation from the original seller. This may not be the case, but it can also fall into the category of you can't please everyone.
Just my dos pesos,