We did... many many times. Perhaps lost a couple hundred dollars because of the narrow window of opportunity to use them. So, as I am starting to do with everything that even smells of an expiry date, I immediately scanned the 20$ Kohl's cash-card using the returnguru Windows Phone App as soon as my wife brought it home. And this was back in Portland!
Once we got to Houston, the obedient reminder came in my email inbox five days before the expiry date of May 13th. We drove up to the nearest Kohl's in League City, TX, and used up the 20$ cash to buy some awesome stuff.
If you miss using the Kohl's cash cards before they expire (the cards usually have a very narrow one week window before they expire), give returnguru a try. You can either email the picture of the cash-card or use our beautiful Windows Phone App for now. iPhone and Android apps are coming soon!