Theres two reasons packages go missing and its not because the postal service lost it. The vendor is scamming, or LEO has profiled his packages (they only need to order a few times from him to do this) and is lifting them along with your information.
In either case you should notify the community of this and switch to a new unwatched/honest vendor. Asking for a reship will confirm with LEO that you are expecting the package.
In short: Never ask for a reship, this is dangerous, and change vendors if anything goes wrong.
I think packages honestly do go missing sometimes. Weather it's a USPS worker stealing yo shit or just something getting lost, packs do go missing. I have had 100% legit packages from ebay go missing.