First, Welcome to the TDR! Glad to have ya! I see you've been lurking around since 2009. . heh
How long have you been doing the 40mile trips? Are they high speed? 40mi might be enough to do a full regen, if you dont have a lead foot. If you havent seen any warning messages within 3-4 months, I wouldnt worry.
Cant do a 'manual' regen, only the dealer can, with the Starscan tool. You can take a good 30minute drive at highway speed, that will do a regen, if needed. Or, let the truck idle in the driveway, after approx 5min of idle, it will ramp up speed and do a regen right in the driveway, again-- if needed.
good luck
-j