This is very common with a Tesla especially if you have the regen set to standard instead of low. It happens because you aren't using your brakes as often as you do in an ICE. Really want a good squeal out of your brakes? Wash your car then take it for a spin, the same will happen once you have been driving in the rain.
To periodically get rid of the noise, put your car in low regen mode and get out on the interstate. Get your speed up to like 60-70mph and brake really hard. Rinse and repeat about 3-5 times and you will be good to go for a while.