1) Have you changed the oil recently? If so what brand of filter?

2)Any unusual top end engine noise? You may want to remove valve covers, adjust valves if apllicable, and ensure the oiler tubes are in place over the camshafts.

I believe if the oil line was comprimised at or near the cylinder head you would notice a rather large puddle of oil accumulating under the car. As well the oil would find it's way to the exhaust system which I believe would create some noticeable smoking at stop signs.

Just my .02