Yeah, especially if you grind your own spices. I use a $20 coffee grinder for grinding dried spices:
http://www.amazon.com/KRUPS-Electric-Coffee-Grinder-Stainless/dp/B00004SPEU/
A chef buddy taught me a few things about spices a year or two ago...I had spices from years & years ago in my cupboard, had no idea they weren't as potent as "fresh" spices. It's obvious now (reading that statement), but spices were always something that I just kept...forever. And even converting different plants, vegetables, and peppers into spices isn't hard at all, and gives the flavor a ton more kick:
http://www.wikihow.com/Make-Cayenne-Pepper
I haven't gotten a ton into it...I have a dehydrator but haven't used it for homemade spice mixes yet. He said 6 months is generally the longest you should go for max flavor, but he does 3 months...way too short for me haha. But then again, his food tastes ridiculously awesome, so...maybe someday