tickled by the fact that i had to push the genius bar to send my phone to the repair depot bc the battery had clearly not worn evenly. you could see in the battery history these precipitous drops and recovery (during which the phone would power cycle but come back 7-10% lower) but the little analysis said it was OK so they couldn't fix it in store. i'd had this exact experience on my galaxy s2 so i knew what was causing it.
they are replacing the phone. they won't tell me why or what was wrong.
it's satisfying to get it solved but frustrating that they didn't just replace the battery.