It took Hermione a long time to calm down after almost being caught in bed with Draco by William Wood. The entire incident was upsetting. Hours after she escaped from Number Twelve and returned to the safety of her own home, she thought about how terrible that entire afternoon could have gone. Despite the fact that she was actively trying to assist one of their leaders in escaping from his inevitable execution, Wood had no desire to follow orders where she was concerned. Given the opportunity to murder the woman who murdered his little brother, he would take it. No doubt he imagined that asking forgiveness later would be easier than obtaining permission before.