2011 Mini S shifting issue
 

I've always liked the Mini Cooper and finally bought a 2011 Mini S. It has an automatic transmission. I've found out that when I accelerate slowly the car shifts from 1st to 2nd very smoothly but if I accelerate quickly it seems to hesitate and then jerks really hard when going from 1st to 2nd but seems okay from on. I'm sure I am not the only one that has experienced this and am hoping someone can tell me what the cause is. Thank you.