We live within 20 miles of a nuclear plant and I bought potassium iodide pills for my family last October!
Last spring I kept having a nagging conscience to buy some KI. I'd blow it off as paranoia, forget about it for a few days and then it would come back stronger than before.
I ended mail ordering some to put my mind at ease. Since 9/11 the price has doubled and there are times when its back ordered and there is a wait.
Its better to have it and not need it than to need it and not have it, IMO.