Is this AT&T rate change minute expiration a new dirty trick?

We use about 1,000 minutes a month on our AT&T mobile family plan. So our use is halfway between their 700 ($48) and 1,400 minute plans ($64).

To avoid overage fees we do the 1,400 min plan, and we now have 1,200 rollover minutes. So I thought I could drop back to the 700 min plan for a while and use them up.

Not so fast ...

On the one hand, I hate AT&T. On the other, I kind of respect the purity of their evil. The rollover minutes are pretty useless, but they were probably a competitive advantage once.

So is this minute expiration policy a new dirty trick, or is it one of their old ones?