Since upgrading from 2.5, I am now getting the following log messages every time I visit the page title config page:

sites/all/modules/page_title/page_title.admin.css - Page Not Found

Comments

Hmm.. I wonder where that file went?! I'll have to see if I can find it. I must have forgotten to "git add"...

Still missing.

To stop filling up the error blog with missing page errors simply uncomment line 39 in page_title-admin-settings-form.tpl.php until this has been fixed.

tecjam is right.
It is in page_title-admin-settings-form.tpl.php.