That's exactly what happened to mine, too. It was my seond Rowenta iron to go bad in less than 18 mos. after purchase; I won't be buying another.
My replacement is a bit bigger, but not as large as many of the irons on the market and cost less than $10 at WalMart. Gets hot, stays hot, no auto off - love it. It's a Proctor Silex Traditions.