Does mocking affect your assertion count?

I'm noticing when I use mock objects, PHPUnit will correctly report the number of tests executed but incorrectly report the number of assertions I'm making. In fact, every time I mock it counts as another assertion. A test file with 6 tests, 7 assert statements and each test mocking once reported 6 tests, 13 assertions.

Here's the test file with all but one test removed (for illustration here), plus I introduced another test which doesn't stub to track down this problem. PHPUnit reports 2 tests, 3 assertions. I remove the dummy: 1 test, 2 assertions.

require_once '..\src\AntProxy.php';

class AntProxyTest extends PHPUnit_Framework_TestCase {
    const sample_client_id = '495d179b94879240799f69e9fc868234';    
    const timezone = 'Australia/Sydney';
    const stubbed_ant = "stubbed ant";
    const date_format = "Y";

    public function testBlankCategoryIfNoCacheExists() {
        $cat = '';
        $cache_filename = $cat.'.xml';
        if (file_exists($cache_filename))
            unlink($cache_filename);

        $stub = $this->stub_Freshant($cat);

        $expected_output = self::stubbed_ant;
        $actual_output = $stub->getant();
        $this->assertEquals($expected_output, $actual_output);
    }

    public function testDummyWithoutStubbing() {
        $nostub = new AntProxy(self::sample_client_id, '', self::timezone, self::date_format);
        $this->assertTrue(true);
    }    

    private function stub_FreshAnt($cat) {
        $stub = $this->getMockBuilder('AntProxy')
                     ->setMethods(array('getFreshAnt'))
                     ->setConstructorArgs(array(self::sample_client_id, $cat, self::timezone, self::date_format))
                     ->getMock();

        $stub->expects($this->any())
             ->method('getFreshAnt')
             ->will($this->returnValue(self::stubbed_ant));

        return $stub;
    }
}

It's like an assert has been left in one of the framework's mocking methods. Is there a way to show every (passing) assertion being made?