So you didnt see the other stand when you walked in? Im guessing if thats the case, they didnt see yours if its a fairly wooded area. At 40 yds it might be hard to pick out if nobody is sitting in it.
I hunt in Northern MN and hunt almost exclusively public land. At first, any little thing people did that I didnt like would p*** me off to no extent, it took me a couple years of realizing that you have to roll with the punches that public land does/does'nt have to offer. I have seen it all, from big jacked up monster trucks plowing their own paths to go cut wood for the winter, to a team of sled dogs behind a roller sled training for races. Sometimes it makes me mad, sometimes I can do nothing but sit there and laugh because its the last thing you would ever think of happening.... On the other hand, deer in that type of environment are a little more used to traffic, noise, etc than an animal on private property that gets very little pressure from other sources.

Wish we could cut wood on public land here. You cant even take trees that have all ready fallen down around here... You can camp there and only burn whats on the ground, or bring in your own. But with the beetle problem, I don't think you can do that anymore. Your not allowed to get firewood from any further than 50 miles away now....

If you gut a deer in public woods, chances are it's going to be near someone's stand at some point. You just happened to be the unlucky one this time. Not many are going to drag a deer home to field dress it.