I WAS DRIVING DOWN THE ROAD BETWEEN 45-50 MPH WHEN SOMETHING HIT ME REALLY HARD IN THE BACK OF MY HEAD. I PULLED OVER AND SAW THAT MY HEADREST HAD POPPED APART. WHEN I LOOKED THIS UP I SAW THAT IT IS A KNOWN PROBLEM AND PART OF THE HEADREST RESTRAINT SYSTEM. I WAS NOT IN AN ACCIDENT, REAR ENDED OR HIT IN ANY WAY AND THE ROAD WAS A SMOOTH ROAD.