A lot of cars do that and it really gets scary when you quickly try to accelerate into another lane when you have an opportunity. I'm not an expert but I think it's the nature of an automatic transmission. When driving in the stop and go traffic, we tend to let off the gas and coast. Since we let off the gas and are still moving, the transmission shifts into the higher gears. Imagine driving a stick shift while idling around 20 miles and hour and have the transmission in 3rd or fourth gear. Then punch the gas without shifting down. I believe that is what is happening to us when this "dogging" out happens.
A solution which you will need to be careful and experiment with is when driving at these speeds is to manually shift the transmission down in to second or maybe first gear. Just remember to shift back up at the proper time so you don't burn up tour transmission.
