Jury Summons

Received a Jury Summons in the mail today. According to this blog, I served on a trial a little less than two years ago. If you've served at any time in the last three years, you're exempt from reporting. Shouldn't the county keep better track of such things, and mail my summons to someone who isn't exempt? They're just wasting money. Plus, it cost me a stamp to mail it back to them.