Man thats too bad, i hate to see fish die.. with your tank being fairly new i wouldn't think that the ich would have come from the new setup. the fish mite have already had it when you picked it up and there is a good possibility it had it before RC, i try and get the fish from them when they are still in the bags when they get the order in. they seem to do better to me, instead of being acclimated a couple times in the same week.
but anyway im sorry about the loss.. =\