Interesting, I thought if you had more than 1 year left on your contract they simply add the $10/month off that lasts for a year. I guess perhaps the way they have it set up is that it might actually change your contract date to 1 year in the future from now which might actually move it back for you if you have a more than a year left currently, so they potentially only do it now for those who have 1 year or less left.
My 3 lines have a little more then a year left.. I added it last month and my own line ends in 09/09/15.
Chat reps are sometimes useless at least he got the 1gig promo!