01 Rio Wet Spark Plug Wire Boot

I just bought an 01 Rio with 89k miles on it. After I drove it home a few days ago I decided to change the spark plugs. When changing out one of them I noticed the wire boot was wet and so was the spark plug. What could be causing that? There is no steam coming out the tailpipe so I wouldn't think it was the head gasket unless it is the beginnings of it.

May be is just water that didnt evaporise from a engine wash.