Bad change between 2nd and 3rd gear

Hi Guys,
 
I drive 2001 VW bora V5 auto. Its started to have a problem changing between 2nd and 3rd gear. There is no noise but the whole car rocks back and forth with the change. It happens after i have been driving for about 15 minutes. Im just hoping for some suggetstions before i yank the whole gear box out to have a look.
 
Thanks