What more than likely happened is this... The DMV does not reset a vehicle's biennial smog check requirement year when a vehicle is bought or sold. The odd or even number year in which its smog check inspection is due does not change. When you bought your Datsun 280Z it needed a smog inspection strictly for the purpose of the title transfer. The biennial smog check requirement was not "reset". So, the vehicle required one smog inspection for the title transfer, and now a second smog inspection in its actual smog check requirement year; and for the purpose of registration renewal, therefore needing a smog inspection two years in a row.
You should verify this information by contacting the DMV at (800) 777-0133. Contact the State Smog Check Referee's Office at (800) 622-7733 if there is any discrepancy with the DMV requirements.
