That bump you would feel is the transmission shifting back into low gear as you stop. What happens is when you take your foot off the gas to stop the transmission will shift into a high gear and coast to save fuel. This is done to get better fuel economy. Then the transmission will get back into low gear as you stop, this is the bump, preparing to take off again. If you have ever let full off the throttle and had the transmission go into high gear then got back hard on the throttle you would notice a delay in the throttle response, that is the computer letting the transmission get back into the proper gear before hard acceleration to keep the transmission safe. This started with the drive by wire throttle.
Jeff