I think it is magnet which acts as sensor for door closing. Yes, you need to glue it back.
Why did it fall, because it was not glues in properly and you are not the first one.
I don’t have a model 3 yet but I recently watched a YouTube video where someone had the same issue, the little diamond piece of “plastic?” fell off.
Not sure if it was related, but he was not able to charge until he stuck it back in place. Again, may have been a coincidence but once he stuck it back in place he was able to charge. While it was out, he couldn’t charge.
Wow, this is crazy. I just logged on tonight to post the *exact* same question, and I see this post at the top of the list.
My 7 y/o son came in from the garage and sheepishly told me that 'a little piece of your car fell off'. He had apparently been messing with the charger door. I agree with the others here - it appears to be just plastic but it must do something more. I hate to bust out the Gorilla Glue on my new Model3, but I guess that's the only way to go.....
Mine fell off last night. It's like Tesla scheduled for these things to come loose at the same time. I got some Scotch Extreme Mounting Tape. Double-sided and super sticky.
I can charge fine without that piece. I can hear the charge port click a couple times before stopping - maybe confused about not detecting that piece. I don't see any errors on screen. I suspect a recent firmware update changed the behavior to continue to allow charging without issue.