I'm at 15,800 miles now and just did a road trip from Atlanta to Charlotte and back. The CEL came on once each direction. In each instance I was cruising a 80 mph and floored it to make a pass. I think my DEF level must be at about half full (it was filled up at the first service at 11K miles). The light again cleared after three starts.

Ard, is this something I need to have documented and checked? Or was it due to my driving style? There are no other symptoms or issues.

As an aside, I had two large passengers, a small dog and luggage and averaged 24.5 mpg at super legal speeds! This truck is awesome!