Oil leaking from #8 header tube?

[HotRodGMC68]

About a month ago I freshened up the top end on my 384 (new springs, seals, had the heads inspected and surfaced, new exhaust seats installed) since then I've been noticing oil coming from around where the #8 header tube is welded into the header flange. My valve cover is not leaking on it. I have no other trace of oil on or around the head. I've pulled the plug out and it's as clean as can be, no trace of oil on it. Also no sign of excess oil making its way into the cylinder. Anyone have any thoughts?

Thanks..