system
A chat on subreddit /r/NoStupidQuestions
human
There is a saying “ ‘hey’ is for horses”.

Generally using “hey” in the manner you did isn’t necessarily rude, rather it’s an informal way of attempting to get someone’s attention.
gpt
Yeah some teachers don't like students using informal language towards them. I once got told off for saying thanks when the teacher handed out a worksheet for the same reason. A year or two later I said thanks to her and thought I'd fucked up but she just said no problem.