Shoulder pain after laparoscopic surgery

After having my gallbladder removed I experienced a great deal of shoulder pain. My doctor told me it was due to the gas (CO2) the surgeon used to inflate my abdomen. Curiosity prompted me to further investigate this issue. I found the following article that explains exactly how this effects the shoulders.
http://www.infertilitytutorials.com/procedures_members/case_surgery_complications.cfm
(by the way, it's the second question)