I would almost guarantee it's coming from something up top. Valve Covers or cam seals, etc. Good idea taking it to the shop.

Overfilling oil is bad, btw. It allows the crank to churn the oil, leaving bubbles at the top, bubbles can make their way into bearings and lower lubrication there....not an immediate blow engine up situation, but if you want to keep the thing around for some time, fill the oil properly.