weird %worldPosition value when passing to a class method

I have the following:

function sceneWindow2D::onMouseDown(%this, %modifier, %worldPosition, %mouseClicks)
{
   echo(%worldPosition);
   $turret.fire(%worldPosition);
}

function turretClass::onLevelLoaded(%this, %scenegraph)
{
   $turret = %this;
}

function turretClass::fire(%worldPos)
{
   echo(%worldPos);
}

onMouseDown will echo out a value like: '-34.166668 -16.875000' while fire will echo out '1311'. Why is the value changing?

If I change the code to:

function sceneWindow2D::onMouseDown(%this, %modifier, %worldPosition, %mouseClicks)
{
   echo(%worldPosition);
   fire(%worldPosition);
}

function fire(%worldPos)
{
   echo(%worldPos);
}

both values are correct. (both '-34.166668 -16.875000')

Why doesn't the first example work?