As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: APPROXIMATELY 30 MIN AFTER TAKEOFF THE FORWARD LAVATORY SMOKE ALARM SOUNDED WITH SMOKE ILLUMINATED ON COCKPIT OVERHEAD. NO SIGN OR SMELL OF ACTUAL SMOKE. ALARM STOPPED AFTER 30 SECONDS. OPERATION CHECK LAVATORY SMOKE DETECTOR.