Ah
Sorry i miswrote that. It wasnt supposed to have the word 'not' in the sentence.
If you have the roof in the open position too long it can cause the creasing to be worse or something like that.
It should have read:
"From memory, which isnt that great these days, I think in the owners manual it says something about you shouldn't have the roof open for x amount of time/days as it will make creasing worse or something like that."