You are not the only one this has happened to. When I bought my Neverfull my tag was also left out. (I think it is happening often) As soon as I got home I noticed it was missing, so I called MOCA LV and they said just come on in and they would give me one. I went the next day and they just looked at the receipt reached into the drawer and handed me one. No questions asked. Very easy, just a pain to have to go back.
Good Luck
Good Luck