Always listen to your gut instinct. ;-)
Something inside of me was screaming that 41.5 pounds was way too high, that something was wrong.
And after looking through all the models again, the error was found; I never manually entered in the weight of the downloaded Colson wheel model, so it used whatever the default density was. This estimated weight ended up being about 1.58 pounds per wheel!
Properly entering in the weight droped the total weight down to 39.30 pounds.
And since I was already on this train of thought, I went back to the specs on the Colson wheels and found that by dropping from 2" width wheels* to the 1.5" width Performa wheels, an additional 1.932 pounds could be lost, bringing the total weight to 37.37 pounds. On top of this, a slight modification to the aluminum inserts pressed into the Colson wheels loses another 0.3 pounds, which brings the weight down to 37.07 lbs. (Which is right in the 36-38 pound range I was expecting).
* The original reason for using the 2" Colson wheels was because we already had a set on our 2008 competition and practice robots; of these the practice robot set would make the migration onto our 2009 practice robot.