Engine hesitation - wet spark plug

[BoomBoy]

I had almost 50,000 miles on the original spark plugs and I was having an engine hesitation under load over 3000 rpm like it was misfiring but no engine code. I decided it was time to replace the spark plugs and I noticed one of the spark plugs (2nd from top in the picture) was wet and darker in appearance (no white). Is there an underlying problem? The misfiring/hesitation problem went away with the new spark plugs.

 

[the duke]

Might be oil given it looks like carbon. Determine if it’s water intrusion past the coil or bypass from the valve cover gasket.