You probably know that credit card companies have been scrutinizing every charge on your account in recent years, searching for purchases that thieves may have made. Turns out, though, that some of the companies have been suspicious of your own spending, too.

In recent months, American Express has gone far beyond simply checking your credit score and making sure you pay on time. The company has been looking at home prices in your area, the type of mortgage lender you’re using and whether small-business card customers work in an industry under siege. It has also been looking at how you spend your money, searching for patterns or similarities to other customers who have trouble paying their bills.

In some instances, if it didn’t like what it was seeing, the company has cut customer credit lines. It laid out this logic in letters that infuriated many of the cardholders who received them. “Other customers who have used their card at establishments where you recently shopped,” one of those letters said, “have a poor repayment history with American Express.”

It sure sounded as if American Express had developed a blacklist of merchants patronized by troubled cardholders. But late this week, American Express told me that wasn’t the case. The company said it had also decided to stop using what it has called “spending patterns” as a criteria in its credit line reductions.