If you are in the Strip and you can't find a better place to buy spices than Penzeys, you gotta be one of the walking dead. Penzeys prices are inflated and their quality is no better than numerous other purveyors in the Strip. And, perhaps the worst thing for foodstuffs that have a very short shelf life, Penzeys does not stamp a date on their products. The store manager can't even decipher the cryptic code on the items, but she will assure you that the goods have an 18 month shelf life. The question is, when did the 18 months begin?
Anyway, if someone who deals in spices tells you ANY spice (except salt) is good for 18 months once it has been ground, ignore them and go elsewhere. There are other purveyors in the Strip that have been faithfully serving customers for decades upon decades.