Agree. If you are holding an E-Ticket that is a valid contract of carriage, I would think that United would have to honor it, unless they did somehow notify you of a dispute in advance.
And a reminder of a tip just for the future, that has been reported here before: On another error fare recently, after United caught it and fixed it, we went surfing at some of the other web booking sites and found that there is sometimes a delay in updating databases, apparently. While getting the error fare via United was over, we did find it still sitting there over at Travelocity and were successfull at snagging and traveling on 4 more itineraries!
