I really don't think so. I've been to plenty of weddings where guests have worn red. A few people wore red to my wedding - it didn't even cross my mind that there was anything wrong with it.
I think the only real no-no for weddings is white/ivory colours for obvious reasons.
I recently wore red to a friend's wedding. Albeit because she asked me and a few friends to do so, so that we'd match the wedding colours. I think red was a nice foil to her white dress.
I've honestly never heard of red being an issue so don't think you have anything to worry about.