The question on Facebook from a clever, cosmopolitan schoolfriend set the alarm bells ringing: ‘If we leave the EU, will it really make it harder for us to move to other countries?'
The answer to this is surely that it might. Yet it's worrying if many young Brits don't know what's at stake.
The thing is, Brits rather like their freedom to move around Europe - but the campaign for Britain to leave the EU has focused heavily on restricting the right of other Europeans to live and work in the UK.
According to a revealing poll by YouGov in December, two thirds of Brits thought they should have the right to live and work in other EU countries - yet only one third believed that other Europeans should have the right to live in Britain.
In other words, Britain is about to go and vote on a subject which, terrifyingly, it can't be bothered to focus on long enough to form a coherent view. The Leave campaign has so far managed to create a vague impression that you can restrict immigration to Britain without equivalent restrictions being placed on Brits who want to move abroad.
Perhaps this reflects the way Brits talk about migration: Brits on the continent are expats; Europeans in Britain are migrants.
Unfortunately for any British diplomats charged with interpreting the will of the people in negotiations, international law doesn't recognize this distinction. As far as the negotiators will be concerned, 100,000 Bulgarian immigrant kitchen fitters have at least the same value as 100,000 sunburnt British expat pensioners.
Let's be clear about one thing: a vote for Britain to leave the EU will be a vote to cut immigration from Europe. It would mean becoming even more detached than Norway or Switzerland, which have pretty much the same immigration rules as EU member states. Immigration is the most important issue for Leave voters and it has been the main focus of the Leave campaign. And if you stop EU citizens coming to Britain, Brits will be prevented from moving to the EU.
This would be a shame: the right to move from one European country to another has perhaps increased Britons' personal freedom more than any other reform since the country joined in 1973. The movement the other way has also been positive – people from the rest of the EU who live in the UK are an asset, paying far more in tax than they take out in benefits.
Like over two million other Brits, I'm biased: I've used this freedom myself – and I'd recommend any fellow Brit to try it. At the age of 21 I hopped onto a train in London, hopped off in Paris and jumped into a job. I then fell in love with a Swede and landed in Sweden, where I launched a career that has been more stimulating than anything I'd have done at home.
There are lots of compelling reasons for Britain to stay in the EU - there's a consensus that it's better for the country's economy, it serves Britain's strategic interests and our allies say it's where we belong.
But these reasons, while vitally important, perhaps don't resonate on an emotional level. But our right to put down roots in Vienna, Rome, Berlin, Krakow or Nice - just because we want to - should. It is a privilege worth protecting, and I suspect young Britons understand this. It's important that they know that this right is at risk.