What was found
AIRCRAFT WAS NOT GROUNDED: 20 MINUTES INTO FLIGHT, FLIGHT ATTENDANT NOTICED FLOOR VERY WARM WITH ASSOCIATED WARM RUBBER/PLASTIC SMELL FROM FLOORBOARD DUE TO HEAT. NO INDICATIONS OF ANY FAILURE WHATSOEVER, EXCESSIVE HEAT PERSISTED FOR REMAINDER OF FLIGHT. HOTTEST POINT WAS 10" AFT CENTERED ON GALLEY CART 1-9. UPON BLOCK-IN, HEAT HAD DISSIPATED. MAINTENANCE REPLACED AVX VENT SILENCER DUCT PER AMM 21-26-42. NO FURTHER DEFECTS NOTED AT THIS TIME.