[Murgatroyd]

I don't see how they can have survived burial for any length of time - a few minutes at most, especially as they still didn't look capable of struggling. If they come back to life, it'll be as lame as Harold Bishop's return to Neighbours, frankly. But there is Locke's highly unsubtle hint. The only sensible interpretation I can come up with is that the graves will be uncovered (all of them, presumably - ick) and they see that the corpses have their eyes open and realise they can't have been dead. Nasty. Or Locke was burbling about the various ghosts or whatever they are.