Shifting transmission into reverse while rolling?

Hi guys and thanks in advance for your response.

I know this is not a generally good habit to have, and I don't do this usually - ever. However, today in a rush and a moment of somewhat stupidity, I shifted into reverse while rolling very slightly forward. I was almost at a full stop.

I know this damages the transmission, but how much damage does one time do? Is it worth stressing over / losing sleep over?

Again, this is out of character for me.
Thanks in advance and have a great rest of your evening.