Probably negotiations. The DOJ let AA-US and the acquiring airlines negotiate payment terms. It's possible it just took longer for VX to complete its negotiations with AA-US. I wouldn't read too much into this.
Piedmont takes over American Eagle operations at DCA effective 5-Jun-14. 60 DCA American Eagle employees given notice. 10 American Eagle flights will remain on the schedule at DCA 5-Jun-14 onward.