Anyway, I took it apart, no problem, and then as I was cleaning the bolt, I turn it over and discovered a hole going through the metal on the underside of the bolt! I gently probed it with a pick and a little piece of metal flaked off. It doesn't seem to be due to rust. In the photo below, the black part you see inside the hole is part of the ejector.

I googled the problem, and I did find one site (cached by google and no longer available) where someone apparently had the same problem with a 597. I'm not sure if the other guy had the exact same hole, because his pics were missing, but it sounded similar. Three responses (below) to his thread seemed to indicate this might not be a major issue, but I wanted to check here before shooting it again.
(responses to the other guy:)
"The hole is caused by machining, not by a materials flaw. It is not a problem, leave it alone and keep shooting."
"It looks like a drill runout, but should not cause any problems. If concerned, I am pretty sure returning the rifle to Remington will get the condition fixed."
"I have had a hole like that in a Browning for 15 or so years and thousands of rounds--nothing to worry about."
Any thoughts?