
Dean was surprised because Theo continued to be silent from earlier, even though he was currently asking the man and his face looked so curious. It's only natural that Dean feels that way, because Theo's presence there is very suspicious and makes him wonder this time.
Ayumi was also speechless, she chose silence and turned away as if she did not want to interfere with the two men. Ayumi is very worried if Dean misunderstands later and thinks Theo has teased him, especially if Dean knows that Theo is the man who had been close to him when Dean was not in the room...