This is a well know phenomenon of the CF6. It is known as "Bloom and droop". It affects both the EGT and N1. Also one of the reason there is a two-stage EGT limit for TO. Usually EGT peaks at around 500' AGL then starts to decrease again. This of course affect the tip clearence and efficiency of the turbine, and this will again affect the N1. So it is not unusual to see a 2% variation of the N1 due to this characteristic.
Also, there is no need to adjust the throttles unless limits are exceeded. Since there is a good N1 margin, it is, as usual, the EGT that tends to be the reason for a bit of throttle pulling.