Parting off on a lathe can cause that. Parting tools like to wander. And there are axial forces at the corner of the insert.
Try to part off a few thou of a brass bar (or plastic, anything that parts cleanly) with a worn tool, in theory the result would be a washer , say, 10 thou thick.
In reality you get a nice little cup like piece. It curls away from the parting tool due to the residual stresses imparted into the metal.
Basically - if you are parting them off...why are you wondering about 0.0005....that aint bad...that is GOOD.
