The accident pilot had been preforming touch and go landings with several trike pilots when he decided to land and talk to another trike pilot on the ground. After landing and setting the parking brake, he exited his trike with the engine still running, to go talk to the other pilot. When he returned to his trike, it had started to move, and he chased after it. As he neared the trike, he attempted to reach around to the right rear strut with his left hand, to stop it. However, the pilot did not see the rear mounted propeller, and his left-hand fingers were struck by the propeller and he was seriously injured. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.