I had a bounty "Get 9000 XP without dying", and my friend Lincolnfrog also had it. He died at the end of a story mission (before it was complete) and I managed to live quite a long time before. When the mission was over, his progress was at 7555/9000 and mine was at 1055/9000 or something very close. That's not possible considering I was alive for about 10 minutes before him, and all he managed to do was complete the mission (which I also did). I've seen this once before. Someone in the fireteam who has the same bounty gets their progress flipped. Perma-linked the mission we did.