Matt -
Your machine probably has ATC - Automatic Temperature Control, or whatever Kenmore calls it, where the mixing valve is thermostatic and it measures the incoming water temperature to some prescribed temp. They do just what yours does - open and close the hot valve to approximate the temperature that it is set at to make 'warm' water. The action there depends on the temperature of the cold water. I've not heard many people here say they like these. The premise behind these originally was to prevent warm from being too warm and thereby causing fading of colors.
I have a 1993 Kenmore machine, and it has true warm rinses where both valves of the mixing valve are wide open when 'warm' is selected. ATC became a more and more common option in the 90s and may be standard now on everything, I'm not totally sure, but I am pretty sure there were still some Kenmores in the later 90s that offerd 'old school' non-thermostatic mixing valves and warm rinse selections, however they certainly were few and far between.
Gordon