In researching the whole "expired FASTPASS" topic, we've used FASTPASSes dating back to 2001. Most CMs look at the return time; few look at the date or year. So if your FASTPASS says "2:40 pm - 3:40 pm," and you return during those times, there's a good chance you'll be admitted. If you're using FASTPASSes printed with 7 pm return times at noon, you're almost certain to be denied.
Disney's official policy is still to ask guests to return during the time stated on the FASTPASS, of course.
Len