Over the years, I've tried researching but haven't run into anything specific. Maybe there are studies but I just haven't seen them. What I've gathered from tidbits and anecdotes here and there and also from talking to a friend who happens to be a doctor is this: my running has resulted in a more efficient cooling system. The body sweats in response to a rise in the core temperature of the body. The more efficient this temperature sensing and subsequent cooling mechanism is, the earlier you sweat. For instance, if you watch the NBA basketball players on TV, they are covered in sweat after about a minute or two into the game. Same logic. Also, the sweat glands are probably more enlarged and possibly more in number as compared to a sedentary person.
The next time this happens to you, think of yourself as a lean, mean, sweating machine. :)
Have to go now, it's time for my afternoon snack -