Flying JFK to LHR on June 29th on Flight 100. Checked in this morning after an upgrade on our short hop from CMH to JFK. When I checked the app on our SWU for the flight 100 portion I noticed our seat assignments in Premium Economy disappeared. Is this something I should be concerned about or reach out to AA about? I have online boarding passes saved to my phone which have the seat assignments. When I view the seat map our booked seats still show occupied. Never had this happen before.