Low-Grade Unrest Question

[TwoBits]

I've got a game situation where I have many provinces suffering from very mild unrest (1-5 points, generally). These are all territories well behind the front lines, and all well within positive dominion. Taxes are set automatically. There have been no reports of spies or other obvious unrest causing events.

Any ideas what could be causing this? I'm EA Pangaea, but have no Revelers in those vicinities - are there other units that are both stealthy and cause passive unrest? Can a Global be causing it (Illwinter is up, and temperatures are down, but like I said, this is all in positive dominion - no visits from frost giants!)? Any other ideas?

Thanks!