As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAV SMOKE EICAS MSG PRESENTED BRIEFLY DURING CRZ. REMOVED FROM SERVICE. AFT LAV SMOKE ALARM REPORTED TO GO OFF. PASSENGER WAS IN LAVATORY AT THE TIME. PERFORMED LAV SMOKE DETECTOR TEST 26-14-01-700-801-A. TESTS GOOD. OPERATES AS NORMAL. NO FURTHER DEFECT. NO PARTS REPLACED. RETURNED TO SERVICE.