I got my tow hitch installed last week by Tesla mechanic (mobile service). He left behind a metal bumper part. It's probably part of the reinforcement for a crash. Is is normal? I wasn't home when he installed it. He also took my bumper cover w/ him and when I called to ask for it. He said normally people don't need it. I am little certain regarding if he did doing it right. Any help or inform will be great. Thanks