What was found
PASSING THROUGH 15,000 FEET ON CLIMBOUT FROM KCOU, THE L REV UNLOCK CAUTION MESSAGE ILLUMINATED. THERE WERE NO BUFFETING OR HANDLING DIFFICULTIES FOLLOWING THE MESSAGE. THE FLIGHT CREW COMPLETED THE QRH WHICH REQUIRED LANDING AT THE NEAREST SUITABLE AIRPORT. THE FLIGHT WAS DIVERTED INTO KSTL. AN OTHERWISE UNEVENTFUL APPROACH AND LANDING WAS MADE INTO KSTL. MAINTENANCE DEFERRED THE LT THRUST REVERSER PER THE MEL AND THE AIRCRAFT WAS RELEASED FOR SERVICE. AFTER RELEASE, THE AIRCRAFT CONTINUED UNEVENTFULLY ON TO KMEM.