Using ActionBar Up Navigation in master/detail fragments

I have an app with master/detail layout (1 activity, 1 ListView fragment and 1 detail fragment). When the user clicks an item in the ListView, a fragment transaction instantiates a detail fragment on the right-pane that includes the information corresponding to that item. When the detail fragment is shown I hide the initial action bar buttons/items and show 3 new AB items (done/delete/cancel). The user can clean the right-pane and return to the initial UI state by either pressing the back button or by pressing one of the 3 AB items.

The issue I'm experiencing is that when the user selects the app's home icon (i.e. "up navigation") the activity gets re-loaded (i.e. the animation that indicates that the activity is starting can be seen as both the action bar and the UI is been redrawn). The issue only happens when the app home icon is pressed. If the user presses the back button or a cancel/done/delete action bar button, the fragment is simply remove from the right-pane and the UI returns to initial state without any "re-loading".

The XML layout for the activity is the following (inside LinearLayout; prettify is hiding that line):

<fragment class="*.*.*.ListFragment"
        android:id="@+id/titles" android:layout_weight="1"
        android:layout_width="0px"
        android:layout_height="match_parent" />

<FrameLayout android:id="@+id/details" android:layout_weight="2"
        android:layout_width="0px"
        android:layout_height="match_parent" />

The DetailsFragement has the actionBar.setDisplayHomeAsUpEnabled statement in its onCreate method:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setHasOptionsMenu(true);


    ActionBar actionBar = getSherlockActivity().getSupportActionBar();
    actionBar.setDisplayHomeAsUpEnabled(true);

}

For both the ListV