If fuel goes up after you buy, then you would have saved $$ because airlines don't collect extra fuel charge when you check in. But when fuel goes down, you can also expect the same "no adjustment" policy.

Jet A is something like $1.35 right now but I heard CX has it hedged at much higher. That might explain the high fuel surcharge because then CX would surcharge you based on the higher fuel cost they are at?