As far as I understand there are no pathogenic moulds that will grow on hard cheese (it is too acidic). Just to be clear, this is not the case for soft cheeses (camembert, brie, some blue cheeses, really soft washed rind cheeses, etc), though. If that starts to go off, throw it out. The pH can get up all the way to 7 on those cheeses, so they aren't safe.