Arts-and-crafts-supplies retailer Michaels Stores admitted Saturday (Jan. 25) that it may have been hit by credit-card thieves. If so, it would be the third major credit-card data breach reported in the past six weeks, following the Target and Neiman Marcus breaches. Firm details about the Michaels data breach, such as how many customers may have been affected or what kind of malware was used, have not been released.