Customers Bancorp postponed the relaunch of its BankMobile app that was slated for January, causing analysts to worry that a plan to sell the digital-only unit this quarter will also be delayed.

"We just decided to delay the launch because of an issue we found with a third party vendor that we want to fully resolve before releasing the app," Luvleen Sidhu, BankMobile's president, said Friday.

"This does not in any way effect our sale/capital raise," she said.

"We are just focused on getting the app out there ASAP since we have built it with passion and excitement," says Luvleen Sidhu, president of BankMobile.

But in a note to clients earlier Friday, analysts at Sandler O'Neill said the postponement of the app update led them to question the first-quarter timetable for the sale of BankMobile.

We believe the potential sale of BankMobile is the primary near term catalyst for shares and this delay could cause weakness in Customers Bancorp shares,” the Sandler O’Neill analysts wrote. “In a conversation with management this morning they suggested that the holdup was related to further testing on security features and that the app could still be out in a matter of days. Management does not anticipate the delay will impact a sale.”

The $9.6 billion-asset Customers Bancorp, based in Wyomissing, Pa., has been rewriting the technology behind BankMobile, its digital-only brand for millennials and technophiles, to replace the Malauzai software the unit has been using since its January 2015 inception.

The bank wanted more flexibility, especially the ability to prove and manage customers' identities its own way and create its own customer onboarding process for BankMobile, which now has 2 million users.

The new version will have stronger security, including the ability to check customers’ identities against 18 data sources, track the location of the applicants' phones and determine if their phones have been jailbroken. It will also have security features that protect transactions, such as one-time passwords sent to the registered phone.

According to Sandler O’Neill analysts, this is the second delay in the rollout of BankMobile 2.0, with the original launch slated for late 2016.

"We are just focused on getting the app out there ASAP," Sidhu said Friday, "since we have built it with passion and excitement and want to share it with our customers."