A patient who received 2 units of A pos pRBCs 2 days ago dev…

A patient who received 2 units of A pos pRBCs 2 days ago developed a fever and jaundice. The post transfusion sample showed DAT positive with monospecific anti IgG. The eluate showed anti Jkb when tested with panel cells. Which of the following explains the positive DAT in the post transfusion sample?