Looking for someone else's experience -

I have a Truglo sight, my wife has a Cobra. On both sights, when you move the individiual pins and then try to tighten them, the pins try to rotate in the direction you are turning the set screw. Neither is a "cheap" sight ($70-$80), and I would expect the machining tolerances to be tighter.

Is this common on other sights, or is this an operator error?