Was my reaction normal?

There's a shared employee bathroom in the back room of my job. If we wanna use it, we knock on the door. If someone says occupied, we go find another bathroom. If there's silence, it usually means the bathroom is empty.

I knocked on the door and no one answered. I waited a few seconds, knocked again and listened to double check. No one answered. I opened the door and went in.

Turns out there was someone in the bathroom. She looks at me and loudly calls me a fucking cunt.

In that second I felt rage and embarrassment, but instead of showing it I smile, grab the roll of toilet paper in there, do a salute gesture, and skip out of the bathroom.

I hear shouting from behind me as I skip away, but I stick to the path ahead.

That was the last roll of TP in there, by the way.

Is it normal?