Bad news if you've recently swiped your credit card at a Barnes & Noble: Hackers broke into keypads at 63 of the bookstores, making off with customers' credit card info. The breach was first discovered on Sept. 14, but kept hush-hush because the FBI was investigating, CNET reports. For now, all 7,000 point-of-sale terminals have been uninstalled from Barnes & Noble stores, and a statement from the company says that customers can still make secure credit card transactions through cash register card readers. Customers are advised to change their PINs and look for suspicious activity on their statements. (More Barnes & Noble stories.)