Finally I have time to write about this learning experience.
A student managed to offend me deeply last week. I knew she was having a hard time understanding what I said in class, but still, when she said something which implied I'm narrow-minded and know little about the world, instinctually my hair started bristling and alarm bells started ringing in my head. It took about two minutes of actively suppressing my anger, probing the student with, to be honest, fairly blunt questions about why she'd said such a bizarre thing bang out of the blue... to find out she'd misunderstood something I'd written on the board regarding light-emitting objects. Somehow she'd understood this as meaning 'recommending something enlightening' (or something along those lines) and was trying to give an example, wanting to say, "If you meet someone who is narrow-minded..."
The after-effects are that I'm still a little suspicious of her (really can't help it) and I'm making more effort to understand what learners are trying to express, instead of listening mainly to what they actually do say.