When I got to work this morning, I got out of my car ('03 WRX sedan), and I noticed a small puddle of oil under the car. I took a closer look and it was dripping from the oil filter seal. I called my wife at home and had her look on the floor of our garage for oil. She said there was about a teaspoon of it on the floor. I then checked my oil level, and it was pretty much empty. There was just a little bit on the very end of the dipstick. So, I think, for whatever reason, that it started leaking from the oil filter last night, and I blew it all out on my way to work this morning (about 12 miles from my house).
First, do our cars have a low oil level light that comes on? If so, mine never did. Does that mean that I'll be okay, assuming I get a new filter and oil before I drive it anywhere? If we don't have a low oil level light, how much damage have I done?