Responding to low-key insult from lecturer A lecturer for a course I am attending was late for a class, and as they had sent an e-mail a few days before mentioning a different classroom, the class was confused about whether we should go to this classroom or not. I decided to send the lecturer an e-mail to clarify whether the class location had changed.

In the end, the lecturer appeared about ten minutes late. That could've been the end of the story, but the lecturer sent an e-mail today (to me only) stating that I "was the only one confused [about the matter]!". I find this rude and inappropriate - they could have just let it slide, or at least apologised for being late.

I realise that I caused some minor noise in their inbox through my e-mail - but it is not enough, in my opinion, to respond rudely.

My University is running a campaign on respect among students and teachers. I would like to respond in a way that clarifies that I think they were rude, while keeping in mind that I will have the class for the rest of the semester with this lecturer.

Should I respond - in that case, how? - , or should I simply ignore it?
Sincerely? Let it go. The tone is also not "low-key insulting" (that means a personal disparaging attack on you), it is dismissive/snotty/irritated (do not bother me with this stuff).

The thing is that you are reading a lot (IMHO too much) into this. I'm not saying that you are wrong, but it sounds that you are in danger of spending precious lifetime for collecting perceived slights. You have already used approx. 1 hour of your lifetime to ask this question, and probably several hours of suppressed anger pondering his answer.

Really, the easiest way is to think "Perhaps he has eaten something bad today/has relationship problems", or whatever. Remember: once is chance, twice is coincidence, thrice is a pattern. If it happens three times, then it is time to act.