Default Usb Port cover missing, can it be replaced?

Hi all, just got my SW2 tonight used! Loving it so far! Unfortunately the previous owner pulled the black part of the port cover off by accident and then lost it. Theres still a clear plastic piece with the bits that actually go into the port. Has this happened to anyone else? I'm worried without the black part moisture may get in? I know the remaining bit does fill the post but with out the black square I'm not sure if it's vulnerable.

What do you guys think? Anyone had this break on them?

I've attached an image of the piece that's left!
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