You're welcome Dreamland - in fact FCOM 1.70.20 page 4 gives a bit of info about it - see below
Protection against fan flutter
. When on ground at low speed (less than or equal to 0.1 MNI. the Electronic Engine Computer (EECI protects against fan flutter. In so doing. the EEC prevents the engine from being stabilized between an approximate range of 60 % to 74 % Nl (depending on the outside air temperature). Therefore, during engine acceleration on ground, the pilot may notice a non-linear thrust response to thrust lever movement.