Dog humping question

Hey! My friends dog was fixed like two days ago. He's humping his blanket girlfriend and all and that is all normal, but why does he want me to watch him? He gets sad when i walk away and keeps looking back at me. Does he want me to applaud him? He's been acting weird and sad around me since and i'm just like not sure what he's expecting me to do I tried to get him inside or get him a treat but he looks at me like I'm betraying him! Is this just him being crazy or does this mean something? Is he gonna hold this against me or something? He's like a really petty dog haha he's held grudges before