1997 Mitsubishi Montero crankshaft Bolt.

I had a complete break job done 2 weeks ago and also 2 cam plugs replaced last week. This morning I started my car. The engine sounded fine, but the 'break light' and a/t light came and stayed on plus I have no power steering. I had it towed to the garage that did the cam plugs. The informed me that the crankshaft bolt had fallen off.
QUESTION: When replacing the cam plugs could anything have been touched regarding the crankshaft bolt?
I'm not a gearhead so I know zilch about mechanical stuff. I just want to make sure that the work I had done did not create the crankshaft deal.
I've owned the car since it was new and I understand there was a recall on the crankshaft bolt in I believe 2000, but I don't remember getting a recall for this item.
Whatcha Think?
Dave