password change logout gives php warnings

Hello,

I have a few issues with the membership plugin. The major one is that it's trying to log out users when they are changing the password from the front end, I get a php warning:

Warning: Cannot modify header information - headers already sent by (output started at /home/***/domains/***.net/public_html/****/wp-content/themes/twentythirteen/header.php:13) in /home/***/domains/***.net/public_html/****/wp-includes/pluggable.php on line 695

It also happens when the custom theme I created is active.