I tried at Soarin' last trip and the CM told me no. I actually hadn't done it intentionally, but DS wasn't feeling great so I took him back to the hotel early for his nap and missed the window. It wasn't a huge deal to me (about the FP), so I told the CM that was OK and also told her the reason I was trying to use it. Then she asked if it was just me (and it was, because DH used his while I took DS back - we took turns taking him for his nap and getting some time to ourselves in the park) and then she said I could use it.
That is a long way of me saying that I think it definitely is possible that they're starting to "crack down" on it. We didn't try to use any other late ones, so I'm not sure. Personally, I wish they would decide one way or the other, publicize it, and stick to it!