MX FormItem doesnt position label correctly when child is label-less Spark CheckBox

Steps to reproduce:
1. Compile and run following MXML example:

<?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"
xmlns:mx="library://ns.adobe.com/flex/halo"
creationComplete="init();">

<mx:Form>
<mx:FormItem label="Spark:" backgroundColor="red">
<s:CheckBox />
</mx:FormItem>
<mx:FormItem label="Spark (with):" backgroundColor="red">
<s:CheckBox label="label" />
</mx:FormItem>
<mx:FormItem label="Halo:" backgroundColor="red">
<mx:CheckBox />
</mx:FormItem>
<mx:FormItem label="Halo (with):" backgroundColor="red">
<mx:CheckBox label="label" />
</mx:FormItem>
<mx:FormHeading creationComplete="event.currentTarget.label = mx_internal::VERSION;" />
</mx:Form>

</s:Application>

Actual Results:
The FormItem label for the Spark CheckBox with no label is misaligned.

Expected Results:
The FormItem label should be consistently aligned. The FormItem label for the Halo CheckBox w/o label is correctly aligned.

Workaround (if any):
Specify a Spark CheckBox label and then set textAlpha=0