Updating: I came out to the garage this morning and it was flat again. Maybe my patch failed (it was raining and I didn't wait long for the rubber cement to dry). Or maybe this tire is a tube assassin.

Here's the timeline:

Sunday night: patched the tube pumped it up to 65 PSI (max for this tire)
Monday morning: squeeze-checked pressure and rode 11 miles to work
Monday evening: squeeze-checked pressure and rode 11 miles home
Tuesday: took a different bike
Wednesday morning: squeeze-checked pressure and rode 11 miles to work
Wednesday evening: tire was flat when I came out from work, patched, inflated to 60 PSI, rode 11 miles home
Thursday morning: flat again