Undefined index in sig_response and reset

Watchdog showing this on a development server. I'm unable to log in if the duo module is activated.

7872426  07/Sep 10:21  notice  php   Notice: Undefined index: sig_response in duo_login_process() (line 81 of /var/www/html/sites/all/modules/duo/duo.module). 
 7872427  07/Sep 10:21  notice  php   Notice: Undefined index: reset in duo_login_process() (line 82 of /var/www/html/sites/all/modules/duo/duo.module). 

Environment:

• Red Hat Enterprise Linux Server release 7.4 (Maipo)
• PHP 5.6.25