Assuming a diamagnetic interaction between a stellar spot-originated localized magnetic field and gas blobs in the accretion disk around a T Tauri star, we show the possibility of ejection of such blobs out of the disk plane. Choosing the interaction radius and the magnetic field parameters in a suitable way gives rise to closed orbits for the ejected blobs. A stream of matter composed of such blobs, ejected on one side of the disk and impacting on the other, can form a hot spot at a fixed position on the disk (in the frame rotating with the star). Such a hot spot, spread somewhat by disk shear before cooling, may be responsible in some cases for the light-curve variations observed in various T Tauri stars over the years. An eclipse-based mechanism due to stellar obscuration of the spot is proposed. With the assumption of high disk inclination angles, it is able to explain many of the puzzling properties of these variations. By varying the field parameters and blob initial conditions, we obtain variations in the apparent angular velocity of the hot spot, producing a constantly changing period or intermittent periodicity disappearance in the models.