He was so angry when she showed up thirty minutes late. What happened was that on that particular day Dane was sick so there was no way she could leave him without attending to his needs. Infact it was from that day Dane started suspecting her because he couldn't believe Sharon would leave him to visit someone else.
She had tried to explain to Freemann but he wasn't one to listen to explaination. They had even had minor fight that day before he finally decided to let go. So his acting all cool to Sharon was very suspicious and unexpected.
Shaw comes back to see Dane standing at the door of the room listening to Sharon having a conversation with someone on the phone.
"What are you doing?" Shaw asked surprised at what Dane was doing.
" Nothing... I am... not.. doing anything" Dane stammared startled by Shaw. He totally forgot Shaw when he came outside to eavesdrop on Sharon conversation with her suppose lover on the phone.