That's the direction I'm heading in, personally. Something big, hard to tell if it's also something bad. Makes the most sense, to me, to point fingers at whatever brought us here, even if they're not doing it directly. Maybe it's a... side effect, or something, or a mistake. Maybe they just can't always get people to stick properly.
Whatever it is that's happening, I don't see how it can be related to the Troubles. We'd know that by now. We'd have found something.