Label doesn't show boldface

Label doesn't show boldface on device when Apache Flex SDK is used with AIR 3.8.
When it is used with AIR 3.6 boldface is shown properly.

I've tried next sample to reproduce it:

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark" applicationDPI="160"
creationComplete="lbl1.setStyle('fontWeight', 'bold')">
<s:layout>
<s:VerticalLayout />
</s:layout>
<s:Label id="lbl1" text="setStyle Bold Formatting" />
<s:Label id="lbl2" text="Normal Formatting" />
<s:Label id="lbl3" fontWeight="bold" text="css property Bold Formatting" />
</s:Application>