I had some seepage from mine and when I pulled the plugs there was more oil around them than I would have liked. If you see any signs of seeping, the gaskets are probably the culprit. Since I've replaced mine, it's spotless down there. OEM gaskets are inexpensive and most shops will charge ~2hrs labor for it. Make sure you get the washers as well, as the rubber on the original ones wears down and compromises the seal eventually.
__________________ '94 Soarer GT-T L
Hardtop/R-154/97+'d/ BPU'd and then some... '92 SC400
JZA80 TT Wheels/Updated to '96 look/Stock winter warrior
it could be both. When you spilled your oil initally, there could've been some left over that you missed while cleaning and just sat in there. As you were driving the oil sitting in the plug valley would work it's way towards the back of the engine under acceleration causing more plugs to be soaked in oil. If it's not burning oil you should be ok, just make sure you clean up what's left of your mess and fix your valve cover gaskets if they are leaking
Its usually the Valve Cover gaskets or if you pour oil and spill it then it will collect on the bottom between the two valve covers by the spark plugs. You would need to pull the intake manifold / throttle body to clean it all up. Hardest part is that EGR valve, everything else is fairly easy.
1993 SC300 - Auto @ 215,xxx - 1JZ future
1995 240SX - R154 w / 1JZGTE - 90% swapped
1987 Mighty Max 4G63 turbo - 20% done
2000 929rr Honda - summer toy