In March American changed the minimum check-in time to 45 minutes prior to flight, from 30 minutes. The airline did not notify customers of this change at the time — no emails, no banners at AA.com, just different information on its website. Neither Delta nor United require this.
It’s part of American’s obsession with “D0” — cajoling employees and inconveniencing customers by making every operational decision not based on precision or rule but based on anything that will promote pushing back exactly at the proscribed minute in the schedule.