Actionscript 3 :: Closure To Make TweenLite Example Work As Desired?

I seem to recall something about pass-by-reference and the Greensock TweenLite class. It's the only thing I can think of that is causing this bit of code to be not working as I intend:

for (var i = 0; i < 10; ++i) {
addItem();
}
public function addItem():MovieClip {
var item:MovieClip = getNewItem();

[Code]...

The trace is outputting the values I expect: an incremental sequence where each number is greater than the last (by the height of the item). However, what I see visually is that all the items end up at the same location (as if newPosY were the same for all instances of the tween.)

The only thing that comes to mind is that newPosY is being passed by reference, so each instance of the tween is actually referencing the very same value. Am I missing something? Or do I need some kind of closure to isolate the scope of my tween property's value?