You went on a hunt alone, and got ambushed by the monsters. You won the fight and killed them, of course, but with a ‘few’ cuts here and there.

Dean had to clean you up, and he was obviously not happy. He had found you after he clearly said to not go alone.

"How the fuck did you even think you could beat them alone? You’ve got cuts all over yourself," he mumbled, wrapping a bandage around your wrist.