This! After a bit of thought I reckon I think this is the only explanation. Not keen on the idea of trying to take this off, anyone any tips? Bet there are all sorts of breakable clips etc.....
my drivers side B-Pillar used to unclip at the top sometimes and make a noise at speed, just needed a good hard shove to clip it back in to place. . . . and if you take them off go careful and they can break.
Its probably not your A-Pillar as they are screwed in from under the rubbers . . . unless you have had a new windscreen recently.