Yes please don't be shy about making a fuss about it. We were trying to be 'polite' and accommodating while they 'attempted' to fix this issue. Six days after disembarking we are still very sick with sinus infections.
If you smell that musty scent as you open the door the first day, don't dismiss it. As a pre-emtive measure, I would block the floor, sink and tub drains immediately (it might help). If it's in the carpet etc... just keep as much fresh air circulating as possible. Crack the cabin door and the balcony door and create wind tunnel for awhile - it did seem to help clear out the room from time to time.
However, fingers crossed you won't have an issue and will have a fantastic cruise.