Unexpected access to a protected object property in PHP

gistfile1.php[345]

<?php 
highlight_file(__FILE__);

echo '<hr />';

class A
{
	protected $_x = 100;
	
	public static function getX()
	{
		$a = new A();
		return $a->_x;
	}
}

class B
{
	public static function getX()
	{
		$a = new A();
		return $a->_x;
	}
}

$a = A::getX();
var_dump($a);

$b = B::getX();
var_dump($b);

?>

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