Motivated by recent experiments, we consider the dynamics of spin-1 spinor condensates after a quantum quench from the polar to ferromagnetic state from varying the quadratic Zeeman field q. We apply the truncated Wigner approximation (TWA) to the spinor system, including all spatial and spin degrees of freedom. For short times, we find full agreement with the linearized Bogoliubov analysis. For longer times, where the Bogoliubov theory fails, we find that the system reaches a quasisteady prethermalized state. We compute the Bogoliubov spectrum about the ferromagnetic state with general q and show that the resulting finite-temperature correlation functions grossly disagree with the full TWA results, thus indicating that the system does not thermalize even over very long time scales. Finally, we show that the absence of thermalization over realistic time scales is consistent with calculations of Landau damping rates of excitations in the finite-temperature condensate.