What was found
LEVEL 1 CABIN DOOR AFT L APPEARED SHORTLY AFTER LEVEL OFF AT FL 370. CHECKED THE DOOR, IT WAS ARMED AND LOCKED, DISREGARD COULD ONLY CHECK FWD CABIN DOORS, LEFT & RIGHT, CHECKED CLOSED AND LOCKED. CABIN PRESSURE GOOD. LEVEL 1 CABIN DOOR AFT L WENT OUT. INSPECTED AFT LEFT CABIN DOOR AND FOUND DOOR ARMING HANDLE OUT OF SEQUENCE WITH DOOR CONTROL HANDLE. PERFORMED CABIN DOOR RESET PROCEDURE IAW MM 52-12-13. AFT LEFT CABIN DOOR OPS CHECKED NORMAL.