The above-mentioned quote refers to when Changez and Erica get into a taxi after having dinner with her parents. Changez isn't feeling friendly enough to speak to the cab driver who he realizes is speaking Punjabi and is a Pakistani. This is abnormal because he more than likely would have said hello to a fellow from his home country and probably struck up a conversation; but, he doesn't because of how he felt about a few comments that Erica's father said about Pakistanis at dinner. At this point in his American journey, he doesn't know how to feel because he likes America, but he finds ignorance and misconceptions everywhere about who he is and about his home country. He is with the girl he is interested in, too, so he probably feel insecure about drawing more attention to himself as a Pakistani by saying hello to the cab driver. This is one of the points in his journey that he is confused, but also shapes his character and perceptions of America.