H1B Premium approved but H4 pending

Hello All,

My H1B Extension was filed with premium processing on March 17th 2017 and as well as my other 2 dependents . My visa is approved and other dependent as well but my wife H4 is still pending. It is filed with California processing center.

wanted to know is this expected like H1 approved but H4 still pending ?

Also as this is premium , so it should have been approved with in one month ?

Appreciate any inputs here