Here ya go. If your cat is not showing any signs of illness and the vet says it's okay to fly, it should be just fine. The only stipulation is that the animal has to be free of disease that is transmissable to humans.
Pet cats are subject to inspection at ports of entry for evidence of infectious diseases that can be transmitted to humans. If a cat appears to be ill, further examination by a licensed veterinarian might be required. There is no rabies vaccination requirement for cats. Following entry into the United States, all cats are subject to state and local vaccination requirements. All pet cats arriving in the state of Hawaii and the territory of Guam, even from the U.S. mainland, are subject to locally imposed quarantine requirements.