Mike - you can't change ADL in post even if you wanted to change it.
In my testing I actually could see the exposure in the camera change with the setting changes. I was using a tripod and not making any changes in camera position. I probably had 50 separate frames in my test.
Perhaps light levels changed slightly or the AF sensor position changed causing a change in metering. If the exposure is the same, something changed in the test conditions. Using flash could have had some impact on the setting.
Try another test with each of the settings and no flash.