I was thousands of kilometres from home, in a country where I knew only a handful of local phrases, but the concern in his Tinder message was universal.
"Disclaimer," my match wrote. "I'm 1.80m should you be considering shoe choice."
I responded: "I have no idea what that is in feet! But I'm wearing flats anyway."
It turns out that 1.8m translates to 5 feet and 11 inches. Why was a man who's nearly 6 feet tall worried that his date might tower over him? At 1.63m, I'm around average height for an American woman; the average American man is 1.75m. (He said I "photograph tall".)
In Portugal, where I was Tinder-swiping on vacation, the average man is slightly shorter (1.7m to the average woman's 1.6m). Even if I were taller and choosing to wear heels, would that ruin our evening? Would he feel emasculated and would I feel it was my responsibility to avoid such a plight?
I should hope not. I had plenty of concerns about meeting a stranger on the Internet - mostly tied to my personal safety. Being taller than my date (naturally or due to footwear) wasn't one of them. Besides, Lisbon's uneven cobblestone streets were hard enough to navigate in flats. I could not fathom heels.
My match's "disclaimer" made me laugh. Height is a thing in online dating - a thing many people care about and some lie about. Some women put their height requirements for a guy in their profile. And sometimes, bizarrely, a person's height is the only thing in their bio, as if that's all you need to know about them. As other outdated gender norms in heterosexual relationships are toppling, why do so many daters still want the man to be taller than the woman?
I've dated men who are shorter than me, those who are my height and those who are taller - and a man's stature has never been the reason a match didn't work.
Yes, in most couples, the man is taller than the woman, but that's partly because, on average, men are taller than women.
And there are certainly exceptions - Nicole Kidman and Keith Urban, for starters. Sophie Turner and Joe Jonas. Pharrell and Helen Lasichanh. You probably know a couple in your own life to add to this list.
Height is associated with masculinity, attractiveness, higher status - and with one's ability to provide for and protect his family. Daters might not be consciously thinking about this as they're swiping left and right.
An informal 2014 survey of students at the University of North Texas asked single students to explain why they preferred dating someone above or below a certain height. It found that they "were not always able to articulate a clear reason they possess their given height preference, but they somehow understood what was expected of them from the larger society".
When I think about daters' preference for the man to be taller, I'm reminded of all the other ways in which relationships are changing that we still haven't quite adjusted to.
We expect a man not just to be taller than his partner, but to make more money than her too - even though, in 40 per cent of households with children, women are the sole or primary breadwinners.
We have dating apps that require women to make the first move, but we still expect the man to pop the Big Question and drive a relationship forward.
Dating apps encourage singles to make quick judgments based on scant information in a profile - information that can be wrong or out-of-date. The real verification happens in person, where people can be physically small with large personalities or tall and exceedingly dull.
As my Tinder date and I walked through the Lisbon streets, we talked about the pros and cons of being single while most of your friends are in relationships and the many ways we've seen good things end.
By the time we said goodbye, I was surprised by how much fun we'd had. He wanted to see me again, but I wasn't sure. There was another distance I was thinking about - one not measured in feet but thousands of kilometres.
• Lisa Bonos is a writer and editor for Solo-ish, a Washington Post blog about single life.