Late last year, FRONTLINE did a great piece on the credit card industry and specifically covered the passage of the Credit Card Accountability Responsibility and Disclosure Act of 2009. The act is a good one, requiring companies to comply with new rules that make rate increases carry a 45 day warning with no retroactive rate changes on balances, and reduce late fees, obscure terms, and other gimmicks the industry is known for.
One drag was that it passed back in May of 2009, but it wasn't set to be enacted for 9 months (on FRONTLINE Chris Dodd claimed he was powerless against lobbyists to make it law sooner), but that happened to be just last week.
The credit card industry, ever the jerks, did everything in their power over the last 9 months to prepare for these new rules. You should probably take a look closely at your recent credit card statements, because chances are your cards slipped up to higher rates with no explanation because it was the last chance companies had to do it before the deadline.
My wife and I have excellent credit and we've both vowed to never carry balances for the past few years (after spending most of college and five years after drowning in credit card debt) so I'm used to seeing low rates that we don't even use because we pay them off, but I was surprised to find my cards now have interest rates of 10%, 17%, and 20% respectively. My wife's has a credit card that is hovering around 20% as well.
In the future, you will be notified but it's probably worth taking a look to see if they tried to get you just before the deadline passed for rate increases requiring 45 days advanced warning.