He never responded to my question clarifying the gap. If it's what I think it is, it isn't something to be concerned about. The steel inner sleeve is what goes tight to either side of the shock mount. The bushing is tight in the shock and won't allow movement. Also, the motion on the shock is up and down not side to side. The stock ones were of similar construction and pressed in, they never moved.
Once you press them in you'll see the amount of force needed and combine that with the fact that there is only up and down force on the shocks not side to side, you'll see that it isn't a concern. Even if they got hit by something and did slide to one side, what would it do? They're still on the bushing and sleeve, not like they can go anywhere.