Checking the Lego Technic forum at Eurobricks I found an interesting discussion about the Lego bushes; this pieces.
Apparently there are two types, one older than the other. But in the discussion they were talking about the orientation of the bushes.
As you have seen in the pics above the top and bottom part are different. Some Lego purist tend to put the bottom (as seen in the first photo) looking outside.
Have you ever heard of this? Do you do it?
I have noticed (It is quite obvious) the difference in the piece, but never thought of changing the side…