WHILE DRIVING ABOUT 65 MPH ON THE OPEN ROAD A HEADLIGHT LENS CAME LOOSE, AND BOUNCED OFF THE PASSENGER SIDE WINDSHIELD. WE DIDN'T KNOW WHAT IT WAS UNTIL WE STOPPED AND EXAMINED THE AUTO. THERE WAS A SLIGHT DENT IN THE POST BETWEEN THE WINDSHIELD AND THE PASSENGER SIDE WINDOW. THE LEFT HEADLIGHT LENS WS EXAMINED AND FOUND TO BE LOOSE. ON THE RETURN TRIP THE LEFT HEADLIGHT LENS CAME OFF. FI MAY HAVE GONE UNDER THE CAR AS I RECALL A SLIGHT NOISE WHILE DRIVING. THE PARTS MAN AT THE DEALER MADE THE COMMENT THAT THIS USUALLY DOESN'T HAPPEN TO CADILLACS AND WHEN IT DOES THEY USUSLLY JUST DROP OFF. THE LENSES ARE SECURED TO THE HEADLIGHT WITH GLUE. APPARENTLY THIS IS COMMON ON OTHER AUTOS. THE REPAIR ENTAILED REPALCING BOTH HEADLIGHT AT A TOTAL COST OF ABOUT $610 PROBLEM. IN MY OPINION THIS IS POOR ENGINEERRING.*AK