http://puu.sh/jXRhx/a0feec08b0.jpg
If you hit the corner of a claim you aren't allowed on, it hits you for one damage. Doesn't seem intended since running into a claim that you aren't allowed on normally just blocks you out.
Back story: Char died to super fast ant I ran back to our village but it was late and most of my friends had logged, he hadn't added my hearth secret yet so I wasn't allowed on his claim. I kept noticing I was randomly taking damage when I walked by that area and pin pointed the cause to be the above.