I've recently read some reports of banks lowering customers' credit limits unexpectedly, and the customers failing to noticed. This can result in all sorts of problems, such as over-limit fees, declined transactions, a drop in your credit score, and also less available credit in case of emergencies.
While I like to think that we should all just pay off our credit cards completely and have a large emergency fund, I understand that is not the reality for some people right now. Keeping an eye on your credit limits seems like a sensible thing to do. I've just checked to make sure that mine haven't changed (they haven't) and I encourage you to do the same.
Here' an article at Smart Money Magazine, Banks Lowering Consumers' Credit Card Limits, that talks more about this potentially important issue.