The background on this story is that the first time the cruise lines imposed fuel surcharges in 2008 they did made the requirement to pay retroactive - even to people who had already paid in full.
Those people brought and won several class action lawsuits saying they were not adequately warned plus had been advised they were already paid in full.
So - this time the cruise line have already pre-warned everyone that the fuel surcharges could come about at any time with no warning. If you are fully paid and they decide to impose the curcharge and you don't pay you could lose your cruise.
I am the editor, but I also speculate, ask questions and play devil's advocate. I reserve the right to change my mind.