Could still use cards stolen, after player had conceded

Player A used [[Villainous Wealth]] on Player B and he cast Player B's [[Sanguine Bond]]. Player B later on conceded, the Sanguine Bond was no longer visible on Player A's board. However it continued to trigger repeatedly after the Player B had conceded (including new casts / triggers put on the stack). And he was able to kill me by repeatedly triggering the Bond.