Transmition Dissengaging ?

[coach]

2008 Audi 2.7tdi Quattro Le-Mans.
When I am slowing down and get to around 20mph I can feel a slight knock like something dissengaging on the transmition or drive system. Is this just me been paranoid or could it be the start of something wearing out? The car drives lovely without any other problems on the drive system.

thanks

 

[HEKTOR]

It could be a worn bush somewhere along the drivetrain. Do you get the noise/feeling under any other circumstances?

 

[Alex C]

does it make the sound when you pull away again?

 

[coach]

does it make the sound when you pull away again?

NO It doesn't seem to do it when you accelerate again and it doesn't seem to do it every time . Its like a bad down change just at the last minute. Could be nothing to worry about.