oil on spark plug

ok so i was cleaning my engine bay up a bit and found oil on my spark plug wire end where it plugs into the actual spark plug. i did some searching and found that it could be a valve cover gasket issue. i had replaced the valve cover gasket when i bought the car myself but only the big rubber gasket that goes around the valve cover. after doing some more searching i found these little circular gaskets that go between each socket.

my question is could this be why im getting oil on my spark plug (the circle gaskets)? and why werent these provided with the valve cover gasket kit when i bought it from hyundai?

03 tib i4 5 spd map based 120,xxx

also oil only in one hole