Oil In Spark Plug Well?

My uncle changed my spark plugs today in my Mazda 626, i have a 6 cyl, and when he got to well #1 there was a considerable amount of oil in the well, but the rest were clean. What would cause this? And is it dangerous to keep driving around like this, will it start a fire? My car has been running fine except for occasional jumping/shaking, but no smoke or anything.