I had a very minor fender dinger that I drove away from this morning
Were you driving your car this morning?
Yes, I was driving my car this morning
You should not leave the scene of an accident. It is better to own up to your mistakes as you may pay a higher price if you lie.
I didn't know it was a bad thing. Should I have stayed there?
Yes you should have stayed and exchanged information with the owner of the other vehicle. If they weren't there then leave a note. It's important for information to be exchanged so that your insurance can pay for any damages you caused.