Oil on Spark Plug Threads

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Hey guys! New to the forum and unfortunately my first post is about noticing a little bit of oil on the passenger side spark plug threads. The car is a 09' with about 63,xxx kilometers on it so it's barely been driven.

I was just doing regular maintenance on the car as I plan to get tuned this upcoming spring. Checked the spark plugs and the driver's side is completely dry. But, when I checked the passenger's side I noticed a bit of oil on just the threads of the spark plugs, with the plug closest to the front of the car being the worst.

Just looking for some advice as to what that may be. I have read on the forums about valve cover gaskets leaking and I refuse to believe that's what it is at such low km. But then again, the gasket may have become brittle over time as the car hasn't been driven all that much.

I should also mention that the spark plugs were swapped out about 3k ago as they were carbon fouled by a bad o2 sensor on the one side.

Attaching photos for reference between the driver's side plugs and the passenger side.

Thanks in advance!