Right I was just making a hot chocolate with my little sister, and she had a spoon of melted chocolate which was dripping everywhere! On me, the kitchen cushions, the floor, the lot! We also have a dog, who was nearby, and chocolate is bad for dogs! So, I politely said 'Oo be careful!' and then I got the typical teenager 'WHAT?!', and then my mum said I was being rude and needed to watch what I was saying! How does that work?! ....
I would move on, your mom obviously got you mixed up in her telling off, not worth feeling fed up about, at the age of 20 it shouldnt worry you to that level.