I think Pip is lost in a fantasy he has about being a "gentleman" and will come to regret his rejection of the people who really care about him. Pip is in the height of his own vanity here, and it is reflected in a new pomposity to his language. He even goes as far as to correct the grammar of Biddy, who was his first teacher. He feels himself being remeasured by society, just as the tailor in town remeasured him for clothing even though he already had Pip's sizes. At the same time, Pip is treating the people he meets differently as well, especially Joe and Biddy. He actually finds himself enjoying the bombastic idiot Pumblechook whom he had hated for most of his life.