I fly SFO-IAH and back at least two times a week and even as a Plat before the UA elites were added to the list it was getting increasingly rare to get an EUA on this route without being in an auto-upgrade fare class. I attributed it to more and more people qualifying for Plat towards the end of the year as well as the possibility that many of the routine flyers on this route were qualifying for Presidential Platinum and thus being first on the list (and eligible 6 days out instead of the usual 5). However, if there is any reason to be suspicious, it wouldn't take much for me to swap my UA 1K# in and see what it does...