Obviously BMW aren't shouting about it any more but because of some sort of design flaw, if you have insufficient "anti-freeze" in your water bottle and the water ices up it can push the washers out a bit with the result that they become loose and the first time you use the headlight washers after the freeze is over, the pressure pops them out.
However, design flaw or not, it could be argued that the driver who can't be bothered to keep his washers from freezing (after all that's why BMW fit heated washer nozzles) - so that he can use them in dirty freezing weather, deserves what he gets.
BMW have actually taken this tack before with people who have had this problem and it seems to vary from dealer to dealer with some even saying that they can test to see if you have genuine BMW washer fluid in the bottle!
Go see the dealer and hope their attitude is positive. This problem never occurs when you have enough washer fluid in the system so at least you will be able to make sure it doesn't happen again.