What was found
AIRCRAFT WAS NOT GROUNDED: LAVATORY SMOKE LIGHT CAME ON IN COCKPIT AND BEEPER CAME ON IN FORWARD LAVATORY, DURING CRUISE. ALL INDICATIONS WENT OUT, CEASED, WITHIN ABOUT 10 SECONDS. NO SMELL, HEAT, OR SMOKE PRESENT IN FORWARD LAVATORY. MAINTENANCE PERFORMED SATISFACTORY OPERATIONAL CHECK OF SMOKE DETECTOR PER AMM 26-14-00.