One set of comments I didn't see was about sanitizing everything else. I don't sanitize my pellets, but I sanitize the hop packaging and the scissors I open them with, the bucket/carboy lid, my hands, etc. before I open the fermentor and dump the hops in. Is this overkill? Probably. But I'd rather spend an extra 5 minutes being paranoid then waste the hours I spent brewing.
Old hops can leave off flavors (oxidation), as will hops exposed to sunlight for an extended amount of time. If your hops aren't vacuum packed and stored cold, they won't last long.