I think I must have assumed at the time that this was the same individual as seen earlier that night, which would explain why I never added this photo. In fact, I discovered while databasing all my old sightings that the two are not just different individuals but different species! (Early in 2015, I used the later date for sightings after midnight; I then switched to using the date of the previous day for all sightings. The moths were in fact found the same night.) This moth I found about 100 minutes after turning off the lights when I went back outside for a moment, and I evidently assumed the Sphinx from earlier had just moved. It must have landed on the siding have been drawn in by the indoor lights; what a lucky find!