Last year I had a GSP-ATL-Europe (forget where) and I wanted longer in ATL. Had work to do and also needed time to get my passport.

Plat line was able to move me to first flight out. Called at 1 AM. Agent took awhile but was very nice. Offered to pay but was told no need.

Rebooked on 530 am flight. Did not make it to the airport. Got there and was rebooked on the next flight. Definitely expected to pay but they were very nice and rebooked me without question.

Maybe I'm just nice to people or have good karma but if there is legitimate reason, it is always fine to ask for help. If they cannot go as far as you'd like - especially if it is pushing the rules - you should expect to follow the published rules. Anything more than that is just a nice bonus.