I agree to what you are saying to a certain extent but I think this subtle change in Zoya is consistent with her character. Earlier, she used to talk back and sometimes to the point of being rude with Asad but since he saved her life from the kidnappers, she has started respecting him more. She has also figured out why Asad is 'Mr Grumpy' and also realizes that he is otherwise a good man. I think that's why she doesn't always give it back to him. To her credit, she still does what she has to do. She hasn't compromised on her actions or principles. She has just toned down her rhetoric because she understands Asad better than before. On the other hand, Asad doesn't respect her as much as she deserves. I think this Mangalpur incident will change that also. Once he knows what she did for Mariam, he will not be such a big chauvinist.