First of all, it is a very good sign that last year's colonoscopy was perfect.
Without knowing if the staging of your cancer changed when diagnosed again in 2005,
or what treatment if any you underwent, it is difficult to respond about the chances of another reoccurrence.
I would recommend continuing to see your physician or physicians regularly specific to your cancer diagnosis.
Also, based on the American Society of Colon and Rectal surgeons it appears your physician is following the standard interval surveillance for undergoing a colonoscopy. However, given your history of colon cancer prior to this last colonoscopy I would recommend discussing with your physician, the pros and cons of waiting another three years to undergo the next colonoscopy.
I would also suggest for anyone with a cancer diagnosis to seek out a second opinion.
Please see the American Society of Colon and Rectal surgeons web link for more details related to screening and surveillance. (http://www.fascrs.org/)