php5 method return reference error?

Howdy,
I'm playing with php5 (from cvs), and came accross a strange error
that doesn't happen with php4. Maybe someone can shed some light on
this for me?

I get the error
"Fatal error: Only variables or references can be returned by reference
in /home/waboring/devel/html/test.php on line 11"

Here is the php code

<?php

class foo {
var $test = 0;
}

class bar {
function &get() {
//both of these fail
//return new foo;
return $this->_buildOBJ();
}

function &_buildOBJ() {
    $obj = new foo();
    $obj->test = 'worked';
    return $obj;
}

}

$bar = new bar;
$foo = $bar->get();
echo $foo->test;
?>

This doesn't happen in php4.
This seems to go away if I change the bar::get() method to

function &get() {
$obj =& $this->_buildOBJ();
return $obj;
}

This seems like a bug to me, since both cases the return value is a
reference of an object?

Thanks Walt