Not sure if this is a bug or a new feature. After the kobold quest another PCs disease or poison progressed while he was next to me, and I made a fort save. No one else said they rolled a save, so I just found it odd.
I know that the disease from the sewers under the Colony could spread from PC to PC by means of proximity, at least. Might have been something like this? Were you standing closer to this guy than the rest?