Wondering whether anyone can help me with the following? Had the car about a week and have noticed what I would consider a slightly strange gearbox trait.

A few seconds after a change up up from 1st to 2nd, the revs fall back for a second time, almost like it has changed up another gear but is still in fact in 2nd. Could this be the torque converter clutch slipping?

Also, sometimes when coasting to a stop or very low speeds, the change down from 2nd to 1st happens with a pretty heavy 'thunk'.