Before retiring and becoming "retarded" and buying a cafe & tea room, I was a sales manager for an industrial instrumentation company. I visited and instrumented a bunch of spice manufacturers, to include McCormicks and I would venture to say, based only on my observations, that high volumn retailers like Sams and Costco have the freshest spices on the market. They buy them, they sell them and, if they don't sell, trash them.
Smaller operations can not afford to do this and will hold spices longer. Again, just my observation.
Mack