What did Martin Van Buren do that was strange?

It is hard to know what this question is aiming at, but a chief oddity of Van Buren's administration vis-a-vis those of other presidents was his widower status. He never remarried after his wife died in 1819. When he became president in 1836, of course he had no First Lady. Therefore, he used his daughter-in-law, Angelica, to perform traditional First Lady duties.
It might also be considered strange that Van Buren did not accept Texas into the union. Once it had gained its freedom from Mexico early in the Van Buren administration, Texas applied to become part of the United States. Van Buren used his congressional allies to block this request. This is strange because it ran contrary to the United States's previous policy of expanding aggressively westward towards the Pacific and acquiring as much territory as possible on the North American continent. However, Van Buren feared allowing Texas into the union would exacerbate tensions over slavery that were already running high.