Im an old player, who recently came back after I heard about the new world generation.
Now after getting enough stuff to make a palisade, I did just that. Except I forgot that it takes 12 hours and not 24 for it to set.
I had originally planned to finish the building sunday night then finish it monday evening when I came in from work. (so that I left almost no time for greifers to seal it)
Unfortunately due to my mixup, when I checked on it monday morning before work I saw that it was ready to extend. I didnt have time to finish it before I had to leave.
BUGGER I thought, so I extended the walls a little and sealed the corner post, in the hope that even if a greifer came along, they wouldnt bother building two cornerposts to break my palisade wall. (all within a claim)
I then went to work and hoped for the best.
When I returned, I found a confusing state of affairs, (see pic) one of the walls had a corner post built on it and it was sealed, but the other was untouched.

I was confused, why would you bother to do this? Why not just build two corner posts? I had already cut out the wood and laid it ready to build.
Or is it in fact a random act of kindness, was someone trying to help me with the construction of the wall?
My own theory is that someone began to greif me and then got bored and wandered off before the job was 100% done.
Any thoughts as to why this has happened?