Line Weights on Plat= Trouble in NC

Weird ... I just posted about a complicated job I did last week that had an overlap, and that is exactly how I showed it. Dark line around the legal I was provided, lighter-line and hatching in the overlap area, and labeled the heck out of it. In my opinion, that plat (different line weights and all) clearly conveys there is a gap and overlap. I'm not sure how changing the line weights is going to make that plat more clear.

What's even more confusing they show a set iron where the two deeds intersect... Tell me what rule of boundary construction this is ?