Where do you get 5%? It was 8.2% the last time I measured. Also, my graph is flat at the top and has a sudden drop; not a gradual loss. This loss was in well less than 100 cycles.
250/265 = 94.3%. Can't use 273 as your starting point as the 8 rated miles over 265 are effectively "bonus" range. It's not surprising that you saw a sudden drop in reported capacity. Estimating capacity without going through a full charge/discharge cycle is difficult.
Either way, it's splitting hairs, IMO, as Tesla is right. You're seeing what appears to be a normal amount of capacity loss given your car's age, mileage and climate.
Batteries should lose capacity fastest the first year. Looks like you are 11 months in and probably 20k+ miles?
IIRC, Tesla estimates 20% after 5 years and 30% after 8 years. You're right at 5% after a year and putting on many more miles than average, but I think you'll still come in under Tesla's estimates by the time year 5 rolls around.
At the very least - I don't think the Miami heat is helping much. At least with Nissan LEAFs, Florida vehicles lose capacity significantly faster than average and it appears that Tesla doesn't cool off the pack in the Model S until the pack gets pretty warm - certainly warmer than Florida temps. Remember, thanks to Arrhenius' equation, rate of capacity loss will double for every 10C increase in temperature.
If you want to maximize your battery life, it can help to keep the SOC as close to 50% as possible, especially in the heat and have the charge finish as soon as possible before you plan on driving.