I woke up at around 4:30 in the morning, because my windows (which are ancient) were rattling. as if there was a heavy wind, which would not have been unexpected in April. Once I was awake, though, I noticed that the bed was shaking. It was definitely the bed, and not, say, me shivering in an unexpected temperature drop. I got up and checked outside, and there was no wind. Gee, I thought, it was just as if it had been an earthquake.
Got up and checked the news. And guess what! It really was an earthquake! Centered just east of St. Louis, magnitude 5.4, which is respectable.
EDIT: Seems that the epicenter was actually on the other side of the state, at the Illinois-Indiana border, and that the USGS has revised it down to 5.2 in magnitude. Which is still respectable, for the Midwest.