help reading my sparkplugs

[roadking]

im getting a little bit of oil residue at the base of the threads opposite of the electrode end, plugs seemed to be burning clean otherwise. motor specs.: gm 350 crate 1200 miles,HEI, plug gap 45*, timing 10 btc. i know oil on plugs can be a sign for valve and piston ware but this is a new motor that i properly broke in, just wondering if alittle residue is normal. engine is running great.