It could be from the front or rear main seals, oil pan gasket, valve cover gasket. Those are usually the main culprits. I really wouldn`t worry about it leaking. If it still gets you from point a to point b and back to point a. Just keep an eye on your oil level. When it starts going through what you think is too much in a day, then it might be time to fix it, if it is worth, or put it out on the back 40 and retire it.