For ImageView, you were giving "100dp" to android:layout_width but in case of TextView, you were giving 140dp...that's why the TextView was not aligning correctly. Now set android:layout_width="100dp"
for TextView, the problem will be solved.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".ScanResults" >
<ImageView
android:id="@+id/productLogo"
android:layout_width="100dp"
android:layout_height="100dp"
android:src="@drawable/wedge_color"
android:paddingLeft="10dp"
android:paddingRight="10dp" />
<TextView
android:id="@+id/productTitle"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:layout_below="@id/productLogo"
android:gravity="center"
android:text="Fluffer Nutter Sandwich"
android:textSize="14sp" />
</RelativeLayout>