Will this Android example be safe to use, memory leak-wise?

When reading up on Fragments, I came across this section on communicating with the activity, which contains the following snippet of code:

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        mListener = (OnArticleSelectedListener) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString() + " must implement OnArticleSelectedListener");
    }
}

Somehow I have the feeling that fragments shouldn't contain a reference to their Activity, but I don't really know where this intuition comes from.

I feel like the code above can cause a memory leak when setRetainInstance() is set to true, because the Activity may restart on orientation change while the Fragment is retained, containing a reference to the old Activity. (Is this true?)

But will this pattern be safe to use with setRetainInstance() set to false?