Follow up:
The tickets were for my daughter and family, so I had her call.
She and hubby realized they wanted to travel a few days later than originally scheduled, not just later that day, so that's what they were going to try for.
She called AA and they easily let her change the ticket to later in the day, but a change to any other day would be considered 'voluntary' and would incur a charge. She got them onto a 2:30pm flight. (When I booked, the only sale tickets left for that day was the 6:30am ones.)
She called me and hubby to report. It was decided that giving up the sale tickets and getting available (we checked) BA tickets for a few days later would be preferred.
She then called Priceline. They had no problem cancelling the ticket pending approval of the airline. I just checked the AA record locator. It was indeed cancelled.
I booked them on AA using BA for 5 days later.
Note that although AA and Priceline written policy seems like a change of less than 60 or 90 minutes won't be easily cancelled, on the phone both were very matter of fact that because of the time change she could change/ cancel her flight.
Thank you all for your advice and encouragement.
