I came to the forum tonight specifically to see if anyone had posted about this! I brought my 2018 SE in to the dealership and they said that it's "flash rust" such as after moisture/rain, as some of you have indicated. The problem is that I can now replicate it almost every single time I back out of a parking spot and it is getting to be quite an obnoxiously loud squeal, and it seems to happen more when I come to a forward stop as well. After a few minutes it seems to be better the rest of the drive and of course is only noticeable at low speeds like parking lots and drive thrus.
The tech said it's because of the open wheel design of the SE which allows more moisture in. I don't think that's acceptable as none of my other vehicles ever had such a persistent problem. It's a very nice vehicle but when it squeaks and squeals in a parking lot, it's a very bad look (sound). I'm at about 13K miles now and the squeaking is happening in cold weather and wet weather, particularly after not being driven for awhile, but it definitely happens regardless of if it has recently rained or not. I didn't notice any squeaking in the summer, either due to the weather or probably just the fact that it was <10K miles at that time.
Is the only fix seriously replacing the rotors? And if so, is there a compatible brand that's specifically resistant to this kind of rust and noisemaking? I'd love to hear more thoughts now that I know I'm not the only one.