Queues can be quite erratic because of the satchel when a role is in high demand. That tank was probably one of many that joined when the satchel popped up. I've had a few occasions where I received a satchel for queueing as DPS. A better way to bribe tanks and healers in would be to gradually increase the base rewards (gold, XP and Valor) for joining LFD on a role that's in high demand. It would help curb the huge jumps between the amount of tanks and healers that join. Right now the system waits until queues are fairly high, then it gives a pretty large bonus reward, followed by a large influx of tanks/healers. It makes queue times very volatile.