Apparently there was a shipping issue where the wrong tracking numbers were sent out to people on 5/31 and 6/3. A Google Play support rep let the good folks at Android Central know that a small number of customers might encounter that message, but that it is incorrect and delivery time is still on track.
A small number of customers were sent a ship confirmation with an incorrect tracking number on 5/31 and 6/3. In these cases the incorrect tracking number may indicate that the package is being returned to sender.
Please disregard this tracking number. Another ship confirmation with the correct tracking number will be emailed to you within 24 hrs. Please reference the tracking number in the ‘Thank You’ section of the ship confirmation.
Please rest assured that your package’s arrival date is unaffected by the incorrect tracking number.
You can go about your day as normal and not have a break down over your white Nexus 4 going back to Google.
Source: AndroidCentral