Possible bug in TextLayout

I've got a simple quiz that needs to be ported from FTE to the TextLayout Framework. To get something approximating TextField.autoSize, I use an ample initial value for height, and then use setCompositionSize to crop the DisplayObjectContainer back down to it's correct size. I have a bunch of Choices which are all parented to a Sprite. I measure that Sprite to put the results under the Choices. In the Choice class, everything looks normal. If I trace the boundaries with the drawing API, they are where I expect them.

The problem is the parent Sprite that contains all the Choice instances. Its height hasn't been updated to reflect setCompositionSize.

Here are the relevant code snippets:

//This class creates each Choice:
_choiceSprite = new Sprite();
_choiceSprite.x = 30;
addChild(_choiceSprite);

var choiceXML:XML = new XML("<TextFlow characterFormat='{choiceCF}' containerFormat='{offsetContainerFormat}'><p></p></TextFlow>");
choiceXML.prependChild(_formats);
choiceXML.p.appendChild(UtilityFunctions.stripTag(_xml));

var choiceFlow:TextFlow = TextFilter.importToFlow(choiceXML, TextFilter.TEXT_LAYOUT_FORMAT);
var choiceContainer:IContainerController = new DisplayObjectContainerController(_choiceSprite, 700, 700);
choiceFlow.flowComposer.addController(choiceContainer);
choiceFlow.flowComposer.updateContainer(choiceContainer);
choiceContainer.setCompositionSize(700, choiceContainer.contentHeight);

//This draws a rectangle the size of contentHeight. It is correctly ignoring the 700px initial height.
with (graphics) {
beginFill(0x000000, 0);
drawRect(0, 0, _choiceSprite.x + _choiceSprite.width, _choiceSprite.y + _choiceSprite.height);
}


//Here is the code that positions the feedback under the choices. Note that in this context, _choiceSprite contains ALL the Choice instances. (In the Choice code above, a similarly-named variable contains the TextFlow).
_feedbackSprite.x = _choiceSprite.x;
_feedbackSprite.y = _choiceSprite.y + _choiceSprite.height + spacing * 2;


For some reason, _choiceSprite is over 700 pixels tall, even though its children are nowhere near that size. If I change the initial value in the Choice class, _feedbackSprite moves accordingly (even though the choices have already been resized).