Yes, after I posted here, I thought it was probably a better question for transportation board but didn't know how to move it. I asked about the grace period because I misunderstood your answer and haven't been to WDW in 7 years. I was wondering if I was wrong about the grace period.
I guess I will take a chance on the grace period. Most posters have been able to use them, although it seems there is the very occasional exception, like your own experience. I will try to make it by 7:15 and if that doesn't work, hope for the best. Most replies indicate I can probably make the gates of MK by 7, it seems, which should give me adequate time. The grace period was just for a few minutes of breathing room if it's close.