When I was going to school down in Champaign, at the Univ of Ill, we had a small quake one afternoon. I was going out of the back door of the house, and thought I had tripped out the door. The farm boys told me it was a small quake. They also said it wasn't uncommon for that to happen in southern Illinois. Now a 4.5 sounds a little out of the ordinary, and if you felt it in Chicago, well, that's pretty unusual.
I'm getting my foil hat on for the rest of the day.