One of my horses used to do this, except he'd hang it in the fence, so the farrier started hammering the heels of his shoes in so that they wouldn't stick so far out the back and it seemed to help. But like you say, sometimes they'll manage to pull 'em off no matter what you do.
Rusty was off all summer, due to illness, so I let him go barefoot. The shoer said his feet were pretty out of balance (what ever that means:), I'm hoping once we get him back right it won't happen too often. I'm sure the farrier hopes so too:). But last year when he was being shoed all the time, that's what he started doing, bending the ends in more. Rusty doesn't over reach at all when I ride, it's just when he's being goofy. I've watched him, he really slings himself around.
Becky