Dust cap? Uh! I guess it is common for manufacturers to forget about 'minor' small details (which can provoke major problems). In general, as far as I know, Tesla’s attention to detail is usually high... It seems you we unlucky. Did you check if other owners have reported similar issues?
Even if that one you found fits, I think you should go to your local Tesla service center to see if they have an original replacement for you. After all, you don't have any fault.
That dust cap, as little it is, as the crucial is for keeping dirt out of the connector.