To be fair, I actually did something similar. I left a number of x1.large instances running for a few days beyond a big event I'd scaled up for. I filed a ticket with AWS and they gave us a refund for about half of it, which was a four figure amount.
I do not and will not link to Facebook posts; any way you can slap this up somewhere else so I can link to it in the "Last Week in AWS" newsletter?