judging from the photo, I would say the small cog is not screwed in all the way. It looks like the gap is pretty big there.

Edit: in other words I disagree that the distance between the cogs looks the same. Granted, it is hard to judge from the angle of the photo, but the amount of thread in there is almost as side as the cog itself. No way that is screwed on all the way. I would snag it, probably just needs to be screwed on.