....I don't have one to check but is it possible that the top part of the door was added to the door after the side channel was in place, so they left it cut to accommodate putting on the top part of the door???
... may be a stupid question but hey, is it possible?
No, that's not possible. It's an interesting thought, but impossible.
Mine was untouched when I got it, and it had the channel all the way around.
