I noticed today when I had the engine cover off, that on the top of the EGR valve theres a sort of 'notch' and evidence that soot had been blown out of it. Not much, but enough to make a sooty mark on the underside of the engine cover.

Is this normal for the valve to blow a bit of soot out, or is my EGR valve due a clean? It was last cleaned by the previous owner at 54k and I'm on 75k now (18 months later)