DEAR MISS MANNERS: I’m a university professor and a woman in her early 30s. I was attending a talk and arrived late. The only place to sit was a small couch, big enough to seat two (or perhaps three, but it would be a tight fit).

A male graduate student arrived a few minutes later. He sat down and stretched out on the couch, putting an arm on the back behind me. This felt incredibly inappropriate and overly familiar — we don’t know each other at all, although he knows I’m a professor because I was part of an introduction session at his graduate orientation.

I worried that it undermined my authority with my colleagues and students. I gave him a look to make it clear I wasn’t comfortable with it, and he removed his arm briefly before putting it back up.

I ended up whispering sharply to him, “Do you mind?” He removed his arm then, but I was left thinking about it and wondering if I could have made the point more politely. What would you recommend? Or was I making too big of a deal of this?

GENTLE READER: Since your more subtle indications were ignored, a sharper second attempt, Miss Manners believes, was warranted.

This student’s manspread/arm-across-the-chair combo was cheeky and presumptuous. Since he did it twice, it is hard to believe that it was unintentional. But even if it had been, as a student, he would do well to learn that optics are important, no matter the intent.

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