servo hunting

My experience with servos is limited, so I'll ask the group here:
If a servo is controlled digitally, is it inevitable or even usual that it
will hunt between two adjacent values? The situation envisioned is if the
encoder is at a point where it near a transition between two values, will
noise or other causes make it switch between them?
If this is so, then why wouldn't hysterisis be used to prevent this?

A colleague is using microsteppers and having great difficulties getting
quiet positioning. The residual vibration level of desired is in the sub
microinch level. Positioning accuracy or precision doesn't have to be that
low, he just doesn't want it moving around once he puts it somewhere.

Elliot Burke