Dog went aggro all of a sudden?

I recently adopted a chocolate lab(5month) and she was inside laying on the floor, I wanted to put her outside but she just laid there and didnt go outside when I told her, she knows "OUT" is to go outside. But she just laid there and when I tried to move her she barked and growled at me. I tried to move her with the broom and she attacked the broom and barked alot. She finally gave up and followed me outside. What went wrong here? Should I give up on the dog or try to show "leader of the pack to it"? I have a husky and I am already leader to it, whats with this guy?