A 20' dent, would definitely be noticeable and would probably hamper the handling and ride of the ship. I hope they find out what caused the failure and can fix it. I'm sure she's not the only one with that system on board.
It gets better. Guess who was aboard when this happened? Mickey Arison, the CEO of Carnival Corporation which owns Cunard. It is one thing for a Captain to have a bad day. It is much worse when the boss is there when the bad day happens.
You know how, when you buy a new car you know it won't be long before the first door ding or windshield crack? You dread the day it won't look pristine and new. Guess it's the same with a new ship. If I were that Captain and the boss was onboard, I'd also stick to the story that the throttle stuck! Poor guy, he'll be a long time living this one down, you know his peers will never let him forget it.
Oh yes, the ragging by the other Captains will be there for a long time. "Well Bill, at least you don't have to worry about the boss sailing with you again. I heard he now checks to see which ship you are commanding before he chooses his ship." "You haven't received your bonus check? Hmmm, that's strange. The rest of us got ours 2 weeks ago."