For once, reading the manual actually worked!
This morning while driving in, the Service Engine Soon light came on in my car. I freaked slightly, but finished my drive and pulled out the manual. After freaking me out for a few paragraphs, it said something along the lines of, if you have re-fueled lately, make sure the gas cap is on tight because this could cause the light to come on. Well, since I live in a neighborhood of a lot of, well, lets just call them hoodlums, I figured maybe someone had screwed with my cap. Low and behold, I walk around the car and it is loose. Whether it was hoodlums or me rushing at the tank last week, I don't know, but I screwed the cap back on tightly, so hopefully the problem is now fixed. Whew!
The funny part is I noticed last week I seemed to be using much more gas than I normally do. I bet it was because the damn cap wasn't on tight. Doh!