We'll let Nasz Dziennik and some very loose translation explain the original incident:
But the real reason for absenteeism Michelle Obama is different and has to be a diplomatic response to the blunders and nietakty errors committed by the president to Bronislaw Komorowski, during his visit to the USA. And especially for being one of the statements undermined the marital fidelity of his wife of U.S. president. Komorowski wanted a joke, but instead provoked international outrage. It is no wonder, then, now that Mrs. Obama does not want to meet with the Polish president.