As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: MOMENTARY ILLUMINATION OF THE MASTER WARNING LIGHT IN FLIGHT WITH AFT LAVATORY SMOKE. NO SMOKE FOUND. ACCOMPLISHED OPERATIONS TEST OF LAVATORY SMOKE DETECTION SYSTEM PER AMM 26-17-00. BOTH AFT LAVATORIES CHECK GOOD AND NO EVIDENCE OF SMOKE.