We've been living together for about 7 months. This morning my girlfriend takes some bread and is about to cut it on my counter. I built this countertop, so I said "Hey Maurice, could you use a cutting board please?"

She moves away rapidly and goes to the couch and I said no please don't, but hey she cuts it on the couch arm.

I'm just kind of like, uhhh what. She says "it's second hand isn't it?" And just cuts

-"No I bought it new"

She then pushes the crumbs onto the ground

I say her name "Mauricccee" in that pleading slightly whiny I can't believe you did that voice

She then tells me to calm down and if she talked to me that way I'd be annoyed too. I respond by saying "no I would totally understand". She then storms off and ignores me the rest of the morning, and before she leaves accuses me of being mad at her for no reason. Did I do something wrong here?

EDIT: for the record, I wasn't mad. In fact I made her coffee afterwards and gave it to her. I didn't leave out anything in the story from my perspective. I'll try to talk to her about it later, hopefully it doesn't blow up