Surprised

I work with a man who is about 20 years older than me. He told me him and his wife like to have sex with other couples. He asked me if I was interested but told him my wife would never go for it, and I was not sure if I wanted my wife to have sex with him. He told me he could get my wife to do it. And at the same time I could have sex with his wife. So one night we met at a lounge in the city. I could not believe how he charmed my wife even though he was much older. She seen I was getting fresh with his wife so she did the same with him. To make a long story short they had rented a hotel room with 2 beds and asked us to stay. His wife was attractive but I got more turned on seeing him giving it to my wife. As she growned when he stuck his penis inside her. I was really surprised. I had sex with his wife but got off more watching the two of them. Is this normal?