If it is a new bike the housings have probably seated themselves and caused a little slack in the cable... there is an adjustment barrel at the rear of the deraileur (if you are looking from the rear of the bike) and I would turn it back / left a quarter turn and go for a ride to see if this remedies the problem and if not try another quarter turn.
You can visually check the setting by looking at the chain when it is running on the smallest cog as it should be square and should not be pulling the deraileur cage left or right... you will see how this barrel adjustment affects that.
Micro adjustments can be done at most levers, but not all.