Textview stops updating its contents after orienta

Question

As the title says, I'm having trouble when updating the contents on my Textview. It all works well, until I change the orientation.

Here is the onCreate of the Activity that holds the Textview:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
    setContentView(R.layout.transacao);

    screenTextView = (TextView) findViewById(R.id.lblStatusTrn);
    screenTextView.setText(screenMessage);

    //...
}

And here is the code that update the Textview:

private void setScreenMessage(String message) {
    screenMessage = message;
    screenTextView = (TextView) findViewById(R.id.lblStatusTrn);
    screenTextView.setText(screenMessage);
}

Even though I keep getting no errors, the Textview doesn't update after I call setScreenMessage. This all happens after the orientation change. If I don't change the orientation, everything works fine.

I already looked into a number of similar questions here, but none of them seemed to work for me.

EDIT 1: I don't know if it is relevant, but the setScreenMessage is called from another thread, through an Handler. Code for the Handler:

public void handleMessage(android.os.Message message) {
   //...
   // This command calls setScreenMessage
   command.execute();
}

EDIT 2: Apparently, using Broadcast did the trick. But that makes me think if it is possible that I had an valid reference to an Activity, even though it is not this reference that is been shown. If that is the case, I might have a useless reference stealing away my memory. Is it possible? Is there a way to check this?