noobie question: On the Northeast Corridor (Regional /Downeaster / Acela) if I buy a ticket with AAA or other discount for like a 5pm train, can i take the 6pm train of the same type if i miss the 5pm train by going to the quicktrak machine and printing the ticket at 5:30pm for instance? Or would I have to cancel the ticket, get a refund, and buy a new one without the discount? thanks!