Since your asking questions I will throw in my .02 cents worth. If my plugs looked like that and I had good baffling, no sagging on extended WOT runs, I would not worry a bit.
Although I "might" richen it a tad, unless the richening muddies up the mid range, then I would not touch anything.
I tend to run a richer oil mixture than most and "usually" have good baffling with low pressure areas for good air extraction. If I run a tad lean I usually have no problems anyway and my low and mid are very clean.