We argue that, with regard to the spin rate of magnetic field structure as a function of latitude, the behavior of the magnetic fields of gaseous planets is more analogous to the Sun than the Earth. Certain Jovian magnetospheric phenomena differ in repetition period by 3%. In order to explain Jupiter's two distinct periodicities, it is hypothesized that the spin period of the planet's magnetic features is a function of both latitude and the size of the feature, with smaller high-latitude features rotating slower than either low-latitude features or the dominant dipole moment. Similarly, the low-latitude planetary spin period of Saturn is shorter than the presently accepted single value because the present value is based on a high-latitude magnetic phenomenon. We should also expect differential rotation of surface magnetic features at both Uranus and Neptune if they prove to have internal dynamo-generated magnetic fields.