I think you have hit the nail on the head there Karon .It's all to do with the new security restrictions on liquids that came in to effect in the last couple of months.
You can't take any containers of liquid exceeding 100mls--this includes toothpastes,mosturisers ect too.Even perfume will be taken from you.Being that it is dutyfree you cannot open the packages until you are in the departure lounge by which time your cases are already onboard so it's a real catch 22.
Cheers laura