That can happen with age, but not in this case, Mark. I've spent a bit of time on this subject because I was disappointed in the change. Currently, I have been smoking year 2014 DC, and it still tastes like more perique than DFK as it did when I was smoking that year's stuff fresh. In fact, that was why I opened the tin. I had to convince myself to an absolute certainty that I was right before I went to Hans about it.
On the same subject, I hear reports that some of the Astley's blends have been altered, too. I have no idea how true that is, but a couple of good friends mine are among those have complained about it. I trust those guys, so I am inclined to believe it. I've also read a couple of complaints about other K&K blends. If they are accurate, it's worth giving second thoughts about what to stock up on for the future.