Do all Technic bushes (3713) have the LEGO label on them? I have just found out that many of my Technic bushes (3713) do not have "LEGO" printed on them. Does this mean they are fake?

I know that many parts were produced in several variations.
Technic bushes didn't always have LEGO stamped on them.

I don't remember exactly when I first noticed this, but some years back they started stamping LEGO onto a bunch of different pieces that didn't previously have it.

I suspect they did this because people were knocking off more and more of their pieces.