Yep me to exactly the same, defect with the material that allows it to collapse than it splits bmw uk was not aware of any issues with the rear boot so I'm told and the updated part is not available yet but in the making ! I've been waiting 4-5 wks however my dealer confirmed there had been several cases now.
The front gaitor is the common one and theres been a few cases, i was told they had holed in a similar way as the rear but most of the bikes had been used in enduro mode thus lifting the suspension and putting stress on the boot than it splits !
As the shaft is sealed i can't see how you would do any harm using it, I'd just keep the area clean or stick a patch on it for time being until the fix is available.