EPR spectra of the triplet Cr4+ in Y2SiO5 were investigated. Rhombic symmetry of zero-field splitting leads to three electron spin terms T-X, T-Y, and T-Z in the absence of the external magnetic field. We have observed the magnetically induced anti-crossing of the terms. In the vicinity of energy level anti-crossing the linewidths and positions of the resonance lines depend on temperature, which is explained by the dynamic Jahn-Teller effect. The temperature dependence of spin relaxation rates is described by the direct spin-lattice relaxation process limited to electron-phonon interactions, where the phonon frequencies are close to the applied microwave frequency.