I had an issue with this just this past month. But first, let me tell you when we cruised in 2016, I still had my temporary permanent resident card that is for a two-year period (I'm Canadian, married an American in 2014), and I was only ever asked to show my current Canadian passport for boarding, as well as for disembarking at the US port. My issue was that the conditional green card expired last May, and I was sent a letter for a one-year extension because they are so far behind in issuing the replacements. I had to use this to travel to Canada last year because at the Canadian border they don't want to see my passport, they want to see my green card for the US. Now it has been a year, and I was not sent another extension, so I was getting worried if I had to unexpectedly travel to my family in Canada. When I called USCIS, I was then told about this magical stamp you needed in your passport or you couldn't work or travel. Glad my husband pointed out it was coming up soon, as I was just expecting to get another extension in the mail. So they never would have told me, it was up to me to find out what to do. I tried every morning for a few days to get an appointment at our local office which is an hour away, and I finally got one and had to go that same day. Took me an hour to get there, half hour in line, half hour to wait after checking in, and then all of 30 seconds for him to stamp my passport. But I'm free to travel and work now, and hopefully they will get my new card to me before I have to do it again next year (yes, he said I have to do the same thing next year if I don't receive my card - they are currently working on April 2016, and mine is May 2017!) Glad to hear your wife got her stamp. My husband's greatest fear is losing me at a border somewhere!