This is an almost text-book example of reverse culture shock, where after living abroad you take on enough of the cultural norms, that home seems almost alien to you.
tl;dr<p>The author was away from home for so long that his new territory felt more like home.<p>Confused and overwhelmed at mixed feelings regarding his return, he felt homesick for the alien culture that he came to enjoy so much, while he was travelling abroad.<p>He was thus disappointed by the inversion of feelings he was originally expecting. He is not happy about returning to America.