Since I was in the middle of holiday traffic I drove on a few miles before I checked it.
When I opened the hood I found the idler pulley had spit out its bearings.
The thing I found most interesting was that there was no warning. There was no squeak or roar before the bearing separated. I have heard others squeak for years without failure.
So I am now recommending that this part be changed as a matter of preventative maintenance. Luckily I was able to drive mine to the perts store and them back to the shop. I would hate to have been stranded in holiday traffic if the belt had slipped off.
See my post on http://induprod.blogspot.com/ for a special holiday offer.