I have multiples sites that I use this plug-in with. It doesn't seem to be happening on all pages. My sites are set up to not use www. at the beginning. If you put http://www.mysite.com it actually goes to mysite.com with no issues.
But when I have a page with the Google Content Experiment option checked and I try to go to http://www.mysite.com/Experimentpage/ it doesnt redirect to mysite.com/Experimentpage/ as it should it throws the following error.
"Warning: Cannot modify header information - headers already sent by (output started at /home/bob/public_html/mysite.com/wp-content/plugins/google-content-experiments/class-wpe-GCE.php:42) in /home/bob/public_html/mysite.com/wp-includes/pluggable.php on line 881"
Let me know if you need more information