Is it normal that my wife let our son touch her tits?

My youngest son 11 years start asking many question related sex physiology since he is studying it in biology. He was till this age most of the time taking his bath with his mother “my wife”. Few month ago a specialist informed my wife that his enquiries about sex is normal and that she should stop let him take the bath with her or spy on her while she put her cloth. So my wife comply to the new rules and go beyond till we stop kissing each other in front of him and shout on me if I try to hang her or squeeze her ass as I used to do. Usually One he pass to kiss his mother and say goodbye before leaving to school. But one day my wife was sleeping in a deep sleep and didn’t wake up when he came and sit near her and give her a normal kiss, viewing that she didn’t react, he gave her another kiss in her mouth. I was in our bathroom shaving when I saw him laying down near his mother and putting his hand on her stomach and start moving it up till reaching her tits. He put his hand around her tits and presses them while he was looking around to check if someone catches him. I look at my wife, that she was still sleeping and did not repost while I thing that she could feel the small hands that was squeezing her breast. Then he move up to leave when he move up the t-shirt of my wife to have a clear view on her breast. He looks at them, and then looks down to her panties. She was wearing a string that let see her big ass and a little bit of her twat. He kissed her again on her mouth while he put one of his hands on her breast and run to catch the bus. I was still looking at him when I realize that my wife open her eyes and closed them again in order not embarrassed him. I look at her she was smiling and enjoyed make him horny.