I discovered this yesterday too. I was able to get some Lego's that were already below retail for another 15% off. I was worried they would cancel the order since I ended up getting almost $70 off with it, but they have all shipped! Based on the other posters from today maybe they fixed their error.
That code was only alive yesterday, and it was a mistake. It was one that was supposed to be for employees only but got leaked to the internet at large. They yanked it late yesterday afternoon.