The mirror has a liquid crystal display that darkens with the command of
the light sensor.  If the mirror has been hit hard or has gotten too hot
the glass will delaminate and the ink settles to the bottom of the
mirror.  I would change it out soon bacuase if it leaks out it will
stain the interior.  If your car has under 36K it should be covered
under warranty.  If you have an extended warranty that covers bumper to
bumper it is covered less the deductible.