Updating a single row by default expands ALL collapsed groups. Removing a single row or inserting a single row does the same. This design lacks granularity: an isolated change to a single row should not cause the expanded/collapsed state of all groups to change.

If the user is focusing on flu cases in New York City and a new flu case is added to the Los Angeles group, why should every group in the grid be expanded? 

 Only the group affected by the change should change its UI state. The grid should listen for the change event of the observed  *row* and if it is felt that a change to the row's data should cause a UI change, only the group to which that row belongs should be changed.