I was saved unexpectedly by my second passport a few months ago when taking a trip from the US to Europe. My US passport was valid for another couple months, bu

I was saved unexpectedly by my second passport a few months ago when taking a trip from the US to Europe. My US passport was valid for another couple months, but at checkin they told me I couldn't use it for an international trip because it needed to be valid for at least the next 90 days from date of travel. Luckily I was able to whip out another passport for them, but I'm sure otherwise I would have been stuck trying to get a rush passport and rebook flights.