DirecTV access cards

DirecTV users: Have any of you recieved an envelope in the mail recently with new access cards for your DirecTV receivers? The letter states that these cards replace the existing that are due to expire soon. When did this start? I've been a DirecTV customer for 3 years and still have the same access cards in my receivers as when I got the service.
Now - I need "new" cards, that must be installed, and the old ones destroyed. No where in the package does it have an expiration date for these cards, and, my subscription anniversary date is February - this is July. Before I contact DTV customer service, I thought I'd see if anyone here has gotten a similar package.
I am still using the same access card I got back in 1996! Never got any notice lately.
Yes I had gotten new cards twice since 97. I don't know when the old ones expired for I usually put the new ones in immediately.
This has happened twice to me. I think they periodically send out new cards and expire the old ones to weed out the 'cheaters' who've obtained cards somehow and are pirating the signals, or the new cards have better security or something, but the whole things sucks cause it's at the inconvenience of all of us loyal and longtime customers.
Dragon is right on with the reason they will do this about every 6 years give or take. It is a security issue. Through away the old card. It will fail in short while.

The p-4 cards are to correct a security issue. I got mine around a year ago and disregarded the notice and periodic pop-ups on my screen. In around 3-4 months, my screen went black in the 8th inning of a no hitter!! I called, they walked me through the transfer, and it did not take!! I am still using my old card! They told me they would reissue p-4 cards, but that never happened. In conclusion, you have time to sit on it.
It's not just Direct TV, it also happens with Dish. I'm on my 3rd Direct TV card at home. The executive apt. I was using last summer had Dish Network cards expire. What I found annoying was that Direct TV expected me to pay a $25 fee for the change of card to update their security. I don't mind them protecting their programming, but I don't wish to pay for it. With no small amount of angry discourse they eventually agreed to upgrade the card for free.
I also received a new card about a month ago. I disregarded it for about a week, until a message came on the screen that I would lose my signal if I didn't install the new card. I think it gave me 30 minutes. So I followed the on screen instuctions and installed the new card. It's pretty painless, so I wouldn't make a fuss about it, they give you the card and don't charge you for it.