Oil spots..

Unless its causing an oil pressure problem or making a mess on the hardwood floors in your garage I'd say it will take a while to leak through $4000 worth of oil. For that kind of $ you can get a remanufactured engine, so I'd also be looking for a new mechanic.

It is probably your rear main leaking which is common on every North* with some miles on them. So what, you have to add oil regardless of whether it is a new north* or an old one. North*'s are designed to use oil anyway so if the drips aren't outragiously flowing out leave well enough alone.