As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAV SMOKE DETECTOR WENT OFF FOR ABOUT 3 MINUTES SHORTLY AFTER TAKEOFF. LAV WAS NOT OCCUPIED AND SMOKE WAS NOT PRESENT. REPLACED THE LAV SMOKE DETECTOR IAW AMM 26-12-11-000/400-801, OPS CKS GOOD. RAN ACFT W/ BLEEDS ON, NO DEFECTS NOTED. RETURNED TO SERVICE.