WTF is wrong with my spark plugs? pics included

[super_pablo_]

So... I got my AP and itv-22's so I decided to change the spark plugs last nite...

As I was removing them I noticed they looked normal around the tip EXCEPT for a very weird looking red tan look on the ceramic insulator part of the tip as well as the curved electrode...
I took some pics last nite.. and you'll have to excuse the lack of focus, but hopefully you will appreciate the important point, which is the color.

I did a bit of research and asked around here for a bit, what could cause this... some suggested low quality fuel, with additives... although Ive only used 91 octane (highest I can get in AZ) fuel.... but from circle K (shoulda known better??)...

I have gased from other gas stations, but id say 95% of the time i get 91 octane from circle K...

im not running meth or anything like that, my only mods are cai, turbo inlet, downpipe (about 1k miles with it) and turboback...
...
I noticed some websites also describe this color to be potentially due to a quick raise in temperature which can melt some metal residue causing it to stick to the ceramic part giving it a tan look... except I dont drive my car too aggresively, and the color is not just brown/tan... but more reddish...

can anyone help on this?
should it be something to worry about?

im definitely gonna try shell gasoline now, and check the new plugs after 1.5k miles or so...
other than that.. should I be worried?

thanks
heres some pics