I don't have any examples at this time myself, but I've seen prints on RC paper (this was at least as much the fault of sloppy machine processing as it was the paper) that were less than 20 years old, and were showing MASSIVE silvering-out. This was caused by incomplete removal of fixer. Probably more likely to occur with machine processed prints (but that was in part what RC was invented for, to enable rapid machine-processing of b/w images, like could be done with color prints). This may be less of an issue for amateur photographers who are not machine processing, but RC still requires more washing than most people think in order to achieve archival results. I used to have a print that was made on RC paper that showed significant silvering-out within five years of creation. I no longer have this print.