Jerky Auto Gear Shift. 2nd to 3rd

I drive a 2006 323i steptronic. 121 000 km on the clock. (had it from new)
Lately I find that the gearshift from 2nd to 3rd is not as smooth as it used to be and rather jerky. It is only the shift from 2nd to 3rd.

Also when I stop at a traffic light the car will select 1st after being stationary for a couple of seconds. The gear selection is often jerky and it feels just like another car nudging one slightly forward?

I tried re-setting the box by keeping a foot on the accelerator and start put pushed in for 30 seconds but had no joy.

Any ideas what this could be?

So...I eventually took the car for a service to the agents and asked them to have a look at the jerky gearshift.

The gearbox showed up a fault on the diagnostic tool and BMW suggested that they wanted to keep the car for a week to remove the gearbox and send it away to ZF for an estimate to repair.

I decided against this and collected my serviced car. Strangely the gearshift is now back to its former silky, smooth self? Really strange considering they wanted to remove the box and sent it away.

Any suggestions...must I just keep my fingers crossed and hope for the best?

I own a 2001 740IL and sporadically the transmission has this jerky movement at 30 mph. It happens around curves turning to the right, or going up moderate inclines. I ask the Service Technician about this, but he didn't know what was wrong. Has anyone else had this problem, and how did you resolve it.