There is such code. Check line 2257-2261 in powerpress.php (main file for plugin). Logic:
if( is_admin() )
register_activation_hook( __FILE__, 'powerpress_admin_activate' );
So essentially only powerpress.php is ever loaded, unless you are in the admin area of your WordPress blog. This logic is there for performance reasons, we take pride in providing a light weight plugin when not in the admin.
The only other case when the powerpressadmin.php file is included is when posts scheduled for the future are processed, which happens at random times based on the internal cron system built into WordPress. This should only occur once, and not repeatedly, and even then it should only happen when the 'future_to_publish' hook is called by WordPress. (Side note, this feature will be going away in PowerPress 3.x, as iTunes has dropped their ping support, which was why this logic was added).
My suggestion is to disable other plugins one by one until you find out what is causing the conflict. You may either have a plugin that is invoking the 'future_to_publish' hook, or forcing WordPress to think the site is in the admin mode (even when it is not).
Please contact me directly at cio [at] rawvoice.com, we would like to get to the bottom of such an issue, and if we know which plugin is causing the issue we will put a warning message in PowerPress settings (which we have for a handful of other plugins).
The next version of PowerPress will move that 'init' hook to 'admin_init', but more alarming is the fact that it shouldn't be occurring in the first place.