[android help] Custom seekbar showing gap in between, on large screens?

I made a custom seekbar using 2 png images for my android app. One image is the background, and other is the bar which shows progress. Both are of the same length and width. On small screens( ~5"), it displays perfectly. But on larger screens( ~8"), a small gap is present on the upper bar, and a small part of the lower bar is visible from that gap, as shown in picture:

I checked the 2 .png files, and there is no problem in them. Also, this gap only shows up on big screened devices. What could be causing this?

Edit: Added the XML for the seekbar area:

    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="0.1333333333333333"
    android:scaleType="fitXY">
    android:id="@+id/imageView2"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:clickable="false"
    android:scaleType="fitXY"
    android:contentDescription="@string/p"
    android:src="@drawable/volbar" />
    android:id="@+id/seekBar1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_centerVertical="true"
    android:layout_margin="10dp"
    android:scaleType="fitXY"
    android:minHeight="5dip"
    android:maxHeight="5dip"
    android:progressDrawable="@drawable/styled_progress"
    android:thumb="@drawable/thumb"
    android:thumbOffset="13.5dp" 
    android:paddingRight="13.5dp" 
    android:paddingLeft="13.5dp"
    android:indeterminate="false" />

.

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