Try to trace it at the USPS site. I haven't ship with Xpresspost for a while, but with Expedited parcel, the no. is traceable on http://www.usps.com And it shows that it was delivered to what city & zip code. That should means it's delivered to the correct address.
With Xpresspost, I believe the first & last 2 letters is different than your receipt. You can check with Canadapost for the exact tracking no. labeled on the package, it might be traceable on the USPS site as well. But no scans will be done on the USPS site until it's succesfully delivered.