I'm glad this generated so many good ideas. My problem was that the hole where the chainstay meets the BB is smaller then the diameter of the stay itself. Any attempt to draw out with a magnet was thwarted when trying to fish it out of that little hole.
In the end, I turned the bike 90 degrees in the stand and shook the mighty hell out of it until the bearing found the hole. It was a lot like trying to get a pick out of the body of a guitar. I agree with a previous poster that if that hadn't worked, I would just leave it. Seems like not a big deal, but when I'm trying to get everything dialed in on my buddy's bike, it just nags at me.
Thanks!