2006 Mini Cooper Downshifts Hard When Warmed Up

Hi, I have a 2006 Mini Cooper S with what I assume is the Aisin tranny, not the CVT. When cold the car shifts fine, smooth as silk. Once it reaches full operating temperature it starts downshifting hard from 2nd to first and then when I take off hard from 1st to 2nd and maybe third. Sometimes it seems to slip between these gears and jerks real hard. Upper gears are fine and smooth. On the interstate if I need to punch it to pass or something it seems to perform as it should and very smooth. Of course the repair shops just want me to replace the tranny but I thought I would research it first. Seems odd that it shifts so smooth when cold. Any help or advice would be appreciated.