We report the discovery of an anomalous flare in a bright blazar, namely, PKS 0208-512, one of the targets of the Yale/SMARTS optical--near IR monitoring program of Fermi blazars. We identify three intervals (1, 2, and 3) during which PKS 0208-512 undergoes outbursts at optical--near IR wavelengths lasting for $gtrsim$3 months. Its brightness increases and then decreases again by at least 1 magnitude in these intervals. In contrast, the source undergoes bright phases in GeV energies lasting $gtrsim$1 month during intervals 1 and 3 only.

The optical--near IR outburst during interval 2 is comparable in brightness and temporal extent to the earlier and later optical flares which do have $gamma$-ray counterparts. By analyzing the $gamma$-ray, optical--near IR, and supporting multi-wavelength variability data in details, we speculate that the optical--near IR outburst during interval 2 was caused by a change in the magnetic field in the emitting region without any change in the total number of emitting electrons or Doppler factor of the emitting region. We also discuss the complex optical-near IR spectral behavior during these three intervals.