Turns out the news of store closures across the country wasn't the worst news to come from GameStop within the past month. A third party alerted the company that data from their online credit card system was being listed on certain websites as being for sale. GameStom confirmed with IGN yesterday that it is indeed looking into the situation, and provided a very generic statement to IGN regarding the entire thing.
At GameStop, the security of our customers' payment card data remains a top priority. GameStop recently received notification from a third party that it believed payment card data from cards used on the GameStop.com website was being offered for sale on a website. That day a leading security firm was engaged to investigate these claims. GameStop has and will continue to work non-stop to address this report and take appropriate measures to eradicate any issue that may be identified.
We regret any concern this situation may cause for our customers. GameStop would like to remind its customers that it is always advisable to monitor payment card account statements for unauthorized charges. If you identify such a charge, report it immediately to the bank that issued the card because payment card network rules generally state that cardholders are not responsible for unauthorized charges that are timely reported.
Short version: If you've used a credit card on GameStop.com, now might be a good time to check your bank account and maybe get a new card.