The KB bushings, NOT shifter is what makes the added noise, there have been people with other shifters + KB bushings that hear the noise. But since you hadn't noticed the whine before the tranny service (or maybe you just started paying attention after the service?) I don't know what that may be.
The KB bushings cause a little rattling noise when in gear and no throttle is applied AND they cause a whine that goes up a little in pitch as you accelerate.