Update! My 12V battery replacement
was covered under warranty! The service advisor said something along the lines of "Sometimes the techs enter the wrong code for that..." I don't know if it's supposed to be covered by the warranty they tack on for CPO cars or if it's because my car is still covered under the original warranty (since my car is only three years old and has 20k miles). The invoice says "Pay Type: Basic Vehicle Limited Warranty." At any rate, here's a screen shot of the invoice, in case it's helpful for anyone:
View attachment 487930
The 12V battery replacement was fast, too - I dropped off the car at 9:15am and it was ready for pickup at 10:45.
They also must have vacuumed my (admittedly dirty) floor mats! Everyone was very friendly too. Props to Tesla Centinela Los Angeles! Tesla is awesome.
Brian