Basically, a man and his wife paid down some debt... the amount was "too large" compared to their previous payments, which set off a "red flag." From the article:
'The balance on their JCPenney Platinum MasterCard had gotten to an unhealthy level. So they sent in a large payment, a check for $6,522. And an alarm went off. A red flag went up. The Soehnges' behavior was found questionable. [...] They were told, as they moved up the managerial ladder at the call center, that the amount they had sent in was much larger than their normal monthly payment. And if the increase hits a certain percentage higher than that normal payment, Homeland Security has to be notified.'