We need more information about the SMART Attributes in order to help you. You need to use software such as SMARTReporter or DriveDx which can show the SMART Attributes on the SSD. Note the free version of SMARTReporter is old and may not be as reliable. If you post the information we can see what is going on.
Also post the MX300's firmware revision which can be obtained with this software.
What version of OSX are you running? Is the error you are seeing being reported by OSX or another app? Where are you seeing this error?
As always you should make sure any important data is backed up just in case.