Hard to say without actually seeing the car. It could be anything. If you're mechanically inclined, open up the hood and look for the leak. Also look under the car for the leak. In any case you should take it to the dealer and have them fix it under warranty.
It turns out the the oil galley plug was cracked. This does not seem to be a major problem with this car, as the technician checked and said that this problem has yet to be reported to GM with other Aveos. All in all, this is a nice little car.