An unpleasant new surprise for Chase Bank customers at old ATMs

You might need to take a pill to figure out if you'll be hit with a surprise ATM fee even if you're a customer of this huge bank.

Customers using Chase ATMs at Walgreens and Duane Reade locations could be getting new notifications that they'll have to pay a surcharge if they try to withdraw their own cash from the machines.

In April, Cardtronics announced it bought 2,586 ATMs from Chase, primarily in Walgreens and Duane Reades, as well at several airports and other retail locations across the U.S.

Pat Kiernan, a weekday morning anchor for local cable television news channel NY1 and a Chase customer, was using a Chase ATM at the Duane Reade inside Penn Station in New York City on Monday morning. He was about to withdraw cash from the machine , but stopped when he saw a notification on the screen saying he would incur a $3 surcharge imposed by Cardtronics.

Previously, Chase customers such as Kiernan were exempt from such fees at stand-alone Chase ATMs in such locations.

"I don't understand how hard it is to take the sign off the ATM before you change the software," Kiernan told CNBC.

@patkiernan: Bad enough that @Chase sold off its convenient Duane Reade ATMs. Beware - they're off Chase network but still have Chase signs. #surcharge

Penn Station is the busiest railway station in North America, serving 1,000 passengers every 90 seconds, according to Railway Technology. The Metropolitan Transportation Authority said the station served more than 50 million riders in 2015. It's the busiest station in the Amtrak system, serving more than 10 million passengers a year. It is also the busiest New Jersey Transit station, accommodating more than 92,000 average weekday boardings.

Weeks ago, Chase's customer service team said via Twitter that "if it has the Chase logo on or around the ATM, then it is a Chase ATM."

@Chase ATM in Duane Reade now says Cardtronics. Will I be charged fee if I use it? 99% of my w/draws are at DRs, branches r inconvenient

@AlykatAlyssa If it has the Chase logo on or around the ATM, then it is a Chase ATM. ^WP

Chase spokesman Mike Fusco, when contacted about Kiernan's situation, told CNBC he would look into why the screens on Chase ATMs reflected Cardtronics ownership while the Chase logo and signage remained.

"From now until early next year, we've been notifying customers on the screens that the machine will no longer be a Chase ATM," Fusco said.

"But as long as the Chase brand remains on the screen, it will remain free for customers."

Fusco later followed up with an email to CNBC that said the "message" on the ATM screen that Kiernan saw "is incorrect."

"And we are working with Cardtronics to fix the issue," Fusco said. "We have confirmed that Chase customers are not being charged and we will continue to monitor."

A Cardtronics spokesman told CNBC the company has been integrating locations into its ATM fleet since its announcement in April announcement. He said the company "expects to have news on the topic of ATM branding later this year."

— CNBC's Dan Mangan contributed to this report.