oil leak inside the car

I have a 2001 Echo with manual transmission. I have recently made a ~450 mile trip to Crater Lake and on the way my wife observed that oil was leaking on her shoes from under the glove box (she was sitting in the front passenger seat). The color of the oil is consistent with the motor oil and I have never observed that leakage before. The oil comes in the car through the engine wiring harness, which is coming straight from the engine. Now, I've heard of oil leaks under the cars, but never heard of leaks inside the car. Has anyone come across the same problem or have any idea what can cause it?
Thanks.