As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED. MASTER WARNING DURING CRUISE AT FL330 LAVATORY SMOKE. ALL 4 LAVATORIES CHECKED BY CABIN CREW AND NO EVIDENCE OF SMOKE. WARNING LASTED LESS THAN 5 SECONDS. PERFORMED RESET ,PER AMM 23-73-00. CABIN INTERCOMMUNICATION DATA SYSTEM MESSAGE 1 CLEARED NO FAULTS.