Boeing
The company was told by one of its suppliers, Mitsubishi Heavy Industries, that a change in its manufacturing process may have led to the cracks, on the wing rib in the planes.
Upon inspection, Boeing did find cracks on some jets, a spokesperson told the Wall Street Journal.
"We are confident that the condition does not exist in the in-service fleet," Boeing said.
"The affected areas are very small and the time required to address the issue will vary between one and two weeks. There may be some delays in deliveries, but we expect no impact to 2014 delivery guidance."
Boeing has previously said it plans to deliver about 110 of the jets in 2014.
This is just the latest in a seemingly endless series of troubles with the plane, which was supposed to revolutionize the industry by delivering new levels of comfort and fuel efficiency.
Mitsubishi builds the carbon fiber composite wings at its factory in Nagoya, Japan, according to the Wall Street Journal.