The A330/340 fuel trim system is designed to put the CG as far aft as possible in the cruise.
The aft CG limit is stored in the FCMC, and during the climb fuel is transferred aft to reach this limit.
Now as fuel is used in the cruise, the CG moves aft. As the aft CG limit is reached, the system transfers fuel fwd to the centre or wing tanks to reach another limit stored in the computor. This will happen regularly through the flight, because as fuel is used from the wing tanks the CG moves aft.