My R line is suffering with the same problem, to a somewhat lesser degree. I had condensation in both rear light clusters, just before Christmas. The car was garaged for 2 weeks whilst we were away, over Christmas/New Year and the vast majority of the condensation has disappeared. However, have now taken car out of garage and will see if the condensation/water ingress comes back.
Dealer has been informed of problem and has asked to kept up to date on this. Will post again, as and when it manifests itself!