The warrant is issued after the dogs hit on the package. Also, customs doesn't need a warrant to open whatever the fuck they want. Yes even the shipping address could be flagged, checking tracking with Tor is a horrible idea whether it is the customer doing it or the vendor doing it. I am thankful that I work with vendors who know not to look up my shipping address on Google Maps with Tor, or to check the tracking on my packages with Tor, but I am under the impression that a lot of noob vendors are under estimating or disregarding the extremely serious intelligence leaks caused by this sort of behavior.