Unsure if you removed the upper plenum when changing plugs; as you would have noticed engine oil in it...some guy’s are mounting dual catch cans between pcv & plenum & others are doing pcv deletes & venting to atmosphere.
It’s a good idea to view & clean out holes before inserting socket to remove plugs; as you could have a gasket seeping & causing some buildup on top side of plugs & wetness on them after removal.
Not uncommon to burn a little oil between changes; but keeping the oil from upper plenum will keep it out of combustion chamber & not allow it to gum up & lower octane rating of fuel.
