Hi Guido.

I understand, thanks. Since my focus at the moment is on county boundaries, I almost certainly haven't edited that relation or its ways, except maybe to unglue one or another node from a boundary way, and that might explain it. Also, as it is an international border, I avoid touching it except for small adjustments of less than a few tens of meters. So, probably that intersection was already there and I didn't notice because the relation was incomplete. History sometimes may fool us. 

-- Fidelis