So I crawled under the tractor yesterday evening after putting the snowblower back on because we are expecting over a foot of snow as an April Fools joke.
I couldn't get to the entire linkage mechanism and realized that I will have to remove the foot mat and some other parts. Not having the time for that, I spray lubed what I could get to and worked the pedal a few dozen times. Unfortunately, it had no effect on the creeping issue.
It seemed like either the damper was not soft enough or that one of the springs was not pulling the pedal back hard enough, but I won't be able to tell for sure until I can take it apart. It could also be a problem with the roller/neutral holder interface but there is no way to get at that from under the tractor.
I will have to wait until the snow is gone to take the thing apart to get at the entire linkage mechanism but I will post here when I do that.