Strict warning: Only variables should be passed by reference in alpha_alpha_process_html

Hi,

I am hoping somebody can enlighten me as to what is happening here. I am receiving the following warning with my recent adoption of aGov. I have installed using acquia dash board.

Error message

Strict warning: Only variables should be passed by reference in alpha_alpha_process_html() (line 454 of /Users/peterhoward/Sites/acquia-drupal/sites/all/themes/agov-7.x-1.0-beta11/profiles/agov/themes/contrib/omega/alpha/template.php).

Any help greatly appreciated.

Thanks,
Pete