Similar thing happened to me while transitioning to the tripleseven.
Called for fl 20 to slow down (ATC req.) and give more stability to the A/S
CN: the book says gear down and then flap 20 on this fleet.
Me: the book don't know that fl.20 Is acceptable and won' t trigger any Messages or FDAP.
Gotta go with the flow and the flaws in this place.....