I am reticent to question you Simon, but are you positive about that? Fuji Quickload Acros is adhered to its leader and trailer with some kind of adhesive, but the film base appears to be identical to standard (non-Quickload) Acros. Which is to say, the same 7-mil PET one finds most black and white sheet film coated on. Fuji's version, although I've measured it with digital calipers and found the thickness specification to be met, is more flexible than other manufacturers' film bases of the same material and dimensions.
Originally Posted by Simon R Galley
Out of curiosity, do you make that statement from special knowledge provided by Fuji or have you perhaps been mislead by the film's higher than typical flexibility?
To the OP's question, a friend of mine stockpiled much pack film when Tri-X was discontinued in that format. Some time later, when removing it from his freezer, making exposures and developing it, he found the negatives unusable. It seems the paper used was not intended for extended storage and had attacked the film. I've no idea what the physical specifications of Fuji's black packet paper are, but wonder whether the film damage could have occurred because of extended contact with something that isn't safe for that situation.