You should always be concerned about any loss. If its just burning a bit from age and hard driving, thats one thing. But if you have an oil leak, it can grow into a bigger leak depending on where it is coming from.

Some times oil will leak onto a body part, then flow into a pocket somewhere when you park in your driveway, this is especialy common if you park on a slope of any kind. You probably don't need to panic about it, but make sure its on the list of things to do soon.