If his ears were gonna be "up ears" you would have had to be very careful about them, taping/gluing them up, etc., when he was a puppy, and the cartilage was forming. Some Shelties ears are natually more UP than others, that's all. There's nothing you can do about it now that he's grown up but love him the way he is!

When the Sheltie at work is very happy (like when I get to work in the morning), his ears get kinda like Kai's ears, only even flatter down, so it looks like he's got no ears at all. Then I say "Where are your ears?" and that (sometimes) makes him prick them back up! Silly doggie!