Unfortunately, this is a case of poor German-to-English translating. The message you're getting is simply alerting you that the readiness status of the passengers' airbag has changed. It's definitely not a malfunction. Now, if you get that message even though no one has entered or exited the vehicle, that would be a malfunction.

FWIW, I'm asked the same question a few times every month, mostly by new owners unfamiliar with this feature.