New spark plus have rust on them?

[93CobraR]

After putting on my new GT-40 heads, I pulled my plugs and noticed they all have a rust look to them, it will wipe of but what is this from? I'm using the Fel-Pro 1101-2 head gaskets. There is no coolant leak, oil looks fine,ect... The heads,plugs, new gaskets, ect... only have about 20 miles on them. The only thing that I did different was run some VP racing fuel, could that cause this? The car runs fine other then that. Everything is dusted in the rust coating including the white porcline peice and electrode. I will post some pictures later to day when I get them. Thanks

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87 GT, 4 inch cowl hood,17x9 Cobra R's/255/45's,GT-40 heads,long tubes headers,h-pipe,Flows,BBK cold air, Mass air,70mm MAF, 1.7's, 1" spacer,underdrive pulleys,Pro 5.0, King Cobra, Adj. fuel Reg., Lakewood Lift Bars,50/50's,subframes, 4.10's.
Best time 12.96
Best MPH 103.42
Best 60' 1.695

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