They are often offered to everyone, but you sometimes have to leave the queue to know they are being given out.
It happened to me at GoG. It was my last half day at WDW, and GoG would have been my last ride, except it went down. I waited about 30minutes, but then I was out of time.
As I excited the queue, I was given a return pass, but it was useless to me. It was a little frustrating though, because there was no announcement made about how long the ride would be down or that return passes were being given out.