We study resonant nonlinear magneto-optic rotation (NMOR) in a paraffin-coated Rb vapor cell as the magnetic field is swept. At low sweep rates, the nonlinear rotation appears as a narrow resonance signal with a linewidth of about ``
300 $\ensuremath{\mu}$G'' ($2\ensuremath{\pi}\ifmmode\times\else\texttimes\fi{}420$ Hz). At high sweep rates, the signal shows transient response with an oscillatory decay. The decay time constant is of order
100 ms. The behavior is different for transitions starting from the lower or the upper hyperfine level of the ground state because of optical pumping effects.