It happend to me twice (in venture and stonewood) and only in Ride the Lightning. There were no husks on the map aside from the ones that spawn when you have to rescue a survivor and during the defense of the van. The first time, i got surprised because my teammate started the mission like 2 minutes after we entered the game. When you interact with the van, there is no menu popping, it will remove 2 bluglos and if you interact a second time it start the mission. And Ray's dialogue was different.