Is this from a stop or at low speeds? I'm guessing the jolt comes in because it's holding 1st gear longer in Sport mode and the programming in sport mode does make shift quality a priority.

My 4.8i today for some reason was shifting a bit hard. In traffic at low speeds, it my 2-3 shift was really harsh and the gearbox was hunting a lot for a lower gear.

The E70 transmission has had some shift programming issues and I'm guessing BMW still needs to work out the kinks.