Confusion by the Dashboard Lights

I was driving recently and my engine light came on. I found this a little odd since I had just had a tune-up, so I looked in the car manual. It said sometimes the engine light comes on if your gas cap isn't on properly. That's interesting. I mean, I guess it's good of them to conserve symbols, but now I'll wonder the next time my seatbelt light comes on if it might really mean I need an oil change.