Created Unassigned: After Installing SP2013 with SP1 Every so often Search fails due to the members of SPSearchDBAdmin being removed from the database role [21167]

After Installing SP2013 with SP1 Every so often Search fails due to the members of SPSearchDBAdmin being removed from the database role and not being added backin.

This happens about once a week.

Anybody any ideas.

I have seen a few blogs about this and all they say is add them back in when they go which is no good on a production system.

Thanks

Nigel