Just got a new 2006 V6 Mustang. It is a 5 speed Manual.....Anyways when I go from first to second gear if I dont do it tottally smooth the car rocks a bit and I get what sounds like a knocking sound from the rear....is this normal?

 

I get the same slack and then knock.......in the lower gears...... not sure if it is normal.....but sure like to know.