I knew that, which makes me probably Dorkier Than Thou. Except I wouldn't have been able to explain it as well as the maven did. I often know what's the correct usage, but am not sure HOW I know it. That kind of stuff seeps in and sticks, whereas more important stuff -- who fought the historic Battle of the Bulge? where did I hide my historical tax records? -- seeps out faster than it can seep it.