This is normal on the 100 and not a problem. TRAC is programmed for about a 10-second continous use cycle. I doubt they program it this way simply to prevent overheating of the brakes. The Hill Decent systems work longer and utilize all brakes whereas TRAC selectively uses the slipping brake.
There's only one place my TRAC has ever shut down off-road. Rice Peak in AZ. Long, steep, and very loose hill climb to the summit. It was wet and the TRAC worked all the way up. After it shut down I stopped for a second then took off again. TRAC worked again for a few more seconds before the road improved.