Titlebar shrinks when I specify a minSdkVersion in AndroidManifest.xml

Question

I am trying to specify the minSDKVersion:

<uses-sdk android:minSdkVersion="5" />

Whenever I add this line, my titlebar shrinks a little bit. Not sure why? When this line is not in my manifest, everything is fine.

<application android:icon="@drawable/icon" android:label="@string/app_name" android:theme="@style/Theme.DarkGradient" android:debuggable="false">
    <activity android:name=".Main"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
<activity android:name="AddStocksActivity">
</activity>
<activity android:name="DetailsActivity">
</activity>
<activity android:name="ChartsActivity">
</activity>
<activity android:name="ARActivity">
</activity>

Update: I noticed when I set the minimum level to 3 the titlebar size does not shrink. Anything above will shrink. Why is this?