Well i'm going to say this just because i've noticed this happens to me.
When you have an item on your character and then you put it on the ah, it will still show on your character until you go into a game.
Then the item will no longer show on the character.
Seeing that the auction has 1 day 11 hours left on it he must have just put it up and not joined/created a game making the item still visible on his character.
Just to let you know.