As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ONE HOUR INTO FLIGHT, PASSENGER NOTICED LIQUID LEAKING FROM VICINITY OF LT OVERWING INBD FUEL CAP. F/O VERIFIED FUEL LEAKING AND CAP SECURE. CAPT AND FLT CONTROL CONCURRED TO RETURN TO ATL. REPLACED NR 1 TANK GRAVITY FILL CAP. LEAK CK GOOD.