As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: RIGHT AFT LAVATORY SMOKE ILLUMINATED INFLIGHT FOR APPROXIMATELY 15 SECONDS AND THEN WENT OUT. LAVATORY INSPECTED BY FLIGHT ATTENDANTS NO ODOR OR SMOKE NOTED. SUSPECT VAPING. PERFORMED AMM TEST PER 26-17-00 FOR OPERATIONS TEST OF RIGHT AFT LAVATORY SMOKE DETECTOR. OPERATIONS NORMAL. ALSO PERFORMED VISUAL CHECK OF LAVATORY SMOKE DETECTOR. NO DEFECTS NOTED.