Unwanted padding around an ImageView

I need to include a header graphic in all of my activities/views. The file with the header is called header.xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent" 
  android:layout_height="wrap_content"
  android:background="#0000FF" 
  android:padding="0dip">

  <ImageView xmlns:android="http://schemas.android.com/apk/res/android"
    android:src="@drawable/header"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_margin="0dip"
    android:layout_marginTop="0dip"
    android:layout_marginBottom="0dip"
    android:padding="0dip"
    android:paddingTop="0dip"
    android:paddingBottom="0dip"
    android:layout_gravity="fill"
    android:background="#00FF00"
    />
</FrameLayout>

Note the android:background="#00FF00" (green), it's just visualisation purposes.

I include them into my views like this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical"
  style="@style/white_background">

  <include layout="@layout/header" />
  (...)

So, when I actually try it out, the result looks like the left image, instead of what it should look like (right):

(1) This - the orange - part is the image/ImageView in question
(2) The unloved green border. note: normally, the green area would be transparent - It's only green because I set the background.

Note the green border around the image at the top; It's part of the ImageView and I just can't figure out why it is there or how I can get rid of it. It set all paddings and margins to