After certain flare issues with some units of Nikon's top model Nikon D750, which were later removed, this high-end DSLR camera posed problems to its users yet again. This time, irregularities that occurred have to do with the shutter. Nikon spotted the said irregularities and stated that all users who had experienced these issues would have their cameras serviced free of charge, regardless of whether the warranty had expired or not.
According to Nikon's service advisory, the issues with the shutter arose with the Nikon D750 units manufactured in October and November of 2014. If there were some shutter issues with these units, this could result in shading in a portion of images taken with the D750. Along with an apology, this Japanese giant stated that problematic units would be serviced and that their shutters would be replaced - of course, without any financial compensation.
Nikon's service advisory also says that this problem occurs only with units with a particular serial number, and that owners can check the serial number of their camera (located on the bottom side) on Nikon's official website. If the serial number of your D750 does not belong to the group of those affected by this problem, you should not worry at all, and you may continue using your D750 camera without concern. In case your camera is one of those to which this issue may apply, you will get further instructions. When your D750 camera gets to Nikon's authorized repair station, the shutter will be examined and replaced, after which your camera will be returned to you - of course, free of charge.
Nikon's service advisory regarding the Nikon D750 can be found on Nikon's official website.