that seems to be the norm now a days since everyone is feeling the pinch. they do periodic checks on your credit and assess your credit risk based on the new report. although you may have not defaulted with them if you have with another, or have more cards with high balances or your debt to credit ratio changed those are all reasons for them to change the terms to your account. i am not sure if they gave you this option or not but normally they tell you if you do not wish to accept the new terms of your account )new interest rate) then to no longer use the card and you can just pay it off at the old rate as long as you have no late charges or are over the limit.
*** you really need to call them then. unless you were given an introductory rate that expired they are not to change the terms on your account without notifying you first.***
