SpeedGod They naturally expire after some number of days I can't remember. So for a while you were just accumulating, but now expect every day a certain number will expire. This whole fiasco was about them having a "server issue" for a period of one week that didn't do that naturally expiring, and then looting hundreds of stones all at once in the name of "correcting" their problem.
Yeah so all I can say is make sure you check in and vote every day or the number will go down to zero on its own. Thems the rules of the game.