Spark Plugs with oily looking residue....is this bad news?

[P11SR20DET]

Well I pulled my spark plugs (NGK Platinum PFR7B) during a routine service, and found three of them having some oily looking residue at the tip of the threads and contacts. Does this imply that my piston rings are becoming worn? If so - what do you recommend I do?

 

[PobodY]

Picture?
It doesn't sound too bad to me; is the car smoking at all? - It could just be a touch of oil from the PCV or blow-by (i.e. it's coming from the intake manifold rather than the cylinders).