I think there's actually a flag in the guide data that says "New Episode" vs. "Rerun" (possibly vs. "Unset"), and that the TiVo uses that flag rather than a comparison between the original date and current date. Otherwise, it wouldn't know that each of the 14 times each week that USA runs the new episode of Psych that it's still a new episode. Of course, it will only record it once, since the "Recently Recorded" filter takes over.

So I think that's also the guide data's fault. Still, the TiVo should be able to work around it.