After Washington became president, he had to move to the country’s Capitol where laws said that he could not keep his slaves after six months, so he repeatedly moved his slaves in and out of the state in order to keep them indefinitely. He even told his secretary to move the slaves “in a way that will deceive both them and the public.”
As a side note… After his death he left his remaining slaves to his wife Martha, and since they were inherited they would belong to her and then be freed when she died. She quickly realized that the only thing between the freedom of these enslaved people and their continued servitude was her own life, so she granted them all freedom immediately except for Oney Judge, who had escaped years earlier after George passed laws to prevent slaves in her specific scenario from ever achieving her own freedom.