My bed is under the window and the bedside table is next to is (obviously!), I have just pulled the bedside table out and half of the back of it was covered in fluffy mould - I thought it was just dust at first but some bits were green. The half that wasn't mouldy was covered by the curtains - but there's no visible mould on the curtains or on the back of the bookshelf which is right next to the bedside table. Why is this? I've wiped it off with an anti bacterial bathroom wipe, is there anything I can do to prevent this happening again.