I killed the messenger who offered to take me to Raedric, and received a major rep drop with Gilded Vale. Strange RP-wise (maybe GV likes vampires?), but fair enough. The bug occurred when I re-entered the map (Raedric exterior) where the event happened, after killing Raedric. I received a message informing me of another major rep drop with GV, without any event to tie it to. I have a save, if that's useful.