The only stat the cache keeps for every item is the time and date it got there. Server down or not, the only way that the cache wouldn't "count" the 2 downtime days would be for the server's calendar to be set 2 days back.
Truth be told, a lot of people lost items in their cache, and it was by all means due to game fault. They should be 100% compensated. I don't know how feasible this is, though...