I mentioned in a beer storage question that oxygen is one of the two beer spoilers. Minimize the exposure to oxygen by leaving little head space in your secondary vessel. If you keg, you can flood the secondary with CO2 before transferring. Carbon dioxide is heavier than air and will protect your beer from oxidation.
That being said, there's not much reason to chase a problem that doesn't exist. Oxidized beer has a wet cardboard or stale cracker flavor. If you don't taste those flavors, relax, don't worry and have a non-oxidized homebrew.
