EDIT: not 60k, but before powertrain warranty is up. This is covered under the powertrain warranty (70k on first gen Gs). Issue applies to both coupes & sedans.
I've ran into a few VQ35DE motors so far that have had oil pooling between the spark plug tube seal and valve cover when removing coil pack over cylinder #6.
http://www.youtube.com/watch?v=G1G1LpksqPM
In the video it is an extreme example of what will eventually happen if there is a leak that goes unchecked. I was just about to swap my plugs out at 60k and also spotted oil pooling at cylinder #6. It's at the dealer right now and they already replaced both valve covers under warranty. I highly recommend pulling out coil pack #6 and confirming you don't have a leak there while you're still under warranty. The spark plug tube seals aren't sold separately, they only come with new valve covers. See the invoice attached:
