If the bike is in regular use, any condensation should clear promptly in an H7 bike, as the light 'breathes'. However, it has been remarkably wet almost everywhere in the UK, which doesn't help, but at least that has limited the amount of salt/gritting. Hopefully you won't need to intervene, but you may need to get the hairdryer out if you plan to lay the bike up over winter - start in a dry garage, dryer on a warm setting, then switch down to take the lamp back to ambient once clear of condensation.
Like knutk says, if it's an LED bike, you may need to lean on the warranty, if possible. As I understand it, these are sealed units supposedly, with a cooling system beneath. Clearly BMW can't be held responsible for the likes of stone or accidental damage.