I tested this on both my local machine and on my live site and it only occurs on my live site. One major difference that I know of between the two is the live site is the version of PHP. Here is the output of php --version for my live site:
PHP 5.2.17 (cli) (built: Feb 1 2012 15:01:30)
Copyright (c) 1997-2010 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2010 Zend Technologies
with the ionCube PHP Loader v4.2.2, Copyright (c) 2002-2012, by ionCube Ltd., and
with Zend Optimizer v3.3.9, Copyright (c) 1998-2009, by Zend Technologies
and here is the output for my local machine
PHP 5.3.10-1ubuntu3.4 with Suhosin-Patch (cli) (built: Sep 12 2012 18:59:41)
Copyright (c) 1997-2012 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2012 Zend Technologies
The important part I think is the live site uses PHP 5.2. Do you do anything that wouldn't work in PHP 5.2?
And to answer your questions, this happens in every browser that is below the threshold, both desktop and mobile. I'm using the latest version of the plugin. And for settings, I've selected to allow the user to hide the popup, link no browsers, and the settings for the browsers don't really matter, it happens on every browser I try (I just make each setting max to test my current browser, chrome 23).