Hi bossa,
check this one:
http://www.pprune.org/archive/index.php/t-385214.html
I had the same problems during climb in my airline, no matter which weight. The problem was ending in cruise and it was starting again during approach with flaps configuration, mainly between conf 2 and 3.
When the a/c went under check D they changed the servojack of the elevator. It was nothing of serious and Airbus itself describes airframe vibration as "comfort concern only".
Have a nice evening,
bio161
