Actually the officer was right. While it is very uncommon for them to ask for an itinerary it is clearly states:

You must also have a round trip ticket indicating return passage to a country* outside the United States.

http://travel.state.gov/content/visa...gram.html#ESTA

So he was right for asking for an itinerary. Usually officers accept itineraries on ipads and smartphones, just pull it up and show it to him, case solved.