Fact is, whole dried spices do in fact “expire” – that is, lose potency and flavor.  It's a slow process, but according to McCormick (the spice merchants) and other sources, after 2-3 years you can expect some loss of flavor. Of course, pre-ground spices lose flavor a lot faster. Because this loss is gradual you might not notice it. This is why some folks date their spice bottles upon purchase.