Abraham Lincoln's cached check

Stored in bank vaults belonging to Huntington Bancshares:

The collection includes checks for as little as $1.56 (from Franklin Delano Roosevelt) and as much as $10,000 (from Samuel Clemens, better known as Mark Twain). The Abraham Lincoln check—made out in the amount of $800 to "Self" and dated April 13, 1865—was perhaps the president's last check. By the end of the next day, he was shot.

The stamp affixed to the left side of the check is an orange 2c Bank Check revenue stamp from the first issue of 1862.  Eight hundred dollars was a lot of money in 1865; I wonder what Lincoln needed it for - perhaps to cover one of his wife's notorious shopping sprees?