Not only are they honoring FPs after the window has passed, but we were actually able to use yesterday's FPs today. Yesterday was a rough day for RSR. It was down three times during the day for 2 hours each, then again from 7:15 or so for another hour plus. At 8:10, with our kids asleep on their feet, we were turned away again, and the CM told us that since it was such a rough day, they'd honor our FPs today. The CM today didn't seem to want to take them, but called someone for approval and got it. He did say this wasn't the norm but that he'd let it go this one time.
The point is . . . if you have FPs, ride RSR when it's running! But, if you keep checking back and it's never running, it can't hurt to ask to use them the next day.