As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE DETECTOR ALARMED FOR 15 SECONDS IN THE L4 LAVATORY, ODOR OF SMOKE DETECTED BY FLIGHT ATTENDANT AND DEAD HEADING PILOT. ONLY HAPPENED THE ONE TIME. SOURCE NOT FOUND. OPS CHECK OF THE LAVATORY SMOKE DETECTOR IAW AMM 26-14-00. NO SMOKE NOTED FROM THE WATER HEATER. OK FOR SERVICE.