Another common leak on these motors is the rear engine cover. It might appear as the oil pan, but if you clean it down and keep an eye on it. The leak will develop at the driverside before anywhere else. I haven't seen a rear main leaking yet (although it's a gasket..so it could) but typically it's the rear cover gasket. The bolts aren't overly tight or locktited from the factory.

When you have that leak, you smile and do nothing about it.