I noticed surface rust on the rivet of the passenger side rear door check arm. Odd the small end of the rivet was on top. The driver-side rear door check arm had the rivet reversed but still rust on the small end. Is this normal to see rust and the rivets reversed for a 2018? BTW no rust on either of the front door check arms. I have only had the car a short time. It is still under factory warranty. Car owned in Maryland.