Like I said in an earlier posting. This is they way the engine was desgined.
ALL experience the same fatigue.
I experienced this same exact thing with my previous car. A Ford Taurus SHO. I have not seen how hard it is to take off the valve covers on a G35, but man it was a PITA to take them off in a SHO.
For the SHO you had better replaced them as a precaution at 60K.
Here was our replacement part.
http://k-mansparts.com/items/taurus-...ak1-detail.htm
Here are various car forums which a lot of people are dealing with.
http://en.allexperts.com/q/Saturn-Re...-plug-well.htm
http://forums.vwvortex.com/zerothread?id=3878889
http://forum.doityourself.com/automo...plug-well.html
http://www.acura-legend.com/vbulleti...-thing-110971/
So at 60K I would replace them. But hey don't listen to me I didn't just go through the same thing for 9 years owning my previous car and replacing them twice in it's lifetime.
I knew mine were going bad in my previous car when I got out after driving and I would smell burned oil. Not that I would trust my not visually checking the plugwells for oil. I just knew my car after owning it for awhile.