This is the face of a kid who just napped for an hour and a half! That's FOREVER in her book lately. It's satisfied and a little smug. Like, "Yeah. I can nap for a long time when I want to. I just like driving you crazy".
Sorry to say but I have no secret to how this happened. It just did. I've been thinking she's going through wonder week 19 (Google it), possibly teething, or just a phase. Who knows. I should probably knock on wood because I imagine her next nap will be another 15 minute fake nap but I'm happy with this one for now.