Nothing out of the ordinary.

All new cables stretch. I usually try to stretch them by stressing them out a bit before they leave the shop, but invariably they will still stretch some more.

If you can't make it back to the shop, here's what you do:

Hang the bike from a rack or a place where you can pedal with one hand and make adjustments with the other.

Shift into the middle ring up front (left shifter) and the smallest cog in the back!

Start pedaling and shift up one click on shifter (in back - right shifter). If the chain doesn't shift into the 2nd cog, turn the barrel adjuster (located on rear derailleur, where cable meets the derailleur) counter clockwise until it wants to start climbing into the 3rd cog, then turn it back in (clockwise) about a full turn to a turn and a half. This will line up the rear derailleur directly under the cog. (When looking at the derailleur from the rear, the upper jockey pulley should line up directly below the cog.)

Then shift through all the cogs. They should be crisp shift going up and down. Do this a couple of times.

If the shifting is slow going up (to the bigger cogs) turn the barrel adjuster out at 1/8 intervals.

If the chain hesitates shifting down, turn in using 1/8 turns.

You'll get to a point where it shifts smoothly both up and down through all the gears.

If it shifts well in the small cogs, but not the big ones or versa-vice, you've probably bent your derailleur hanger and should take it into the shop for adjustments.

Good Luck
L8R

BTW congrats on the new bike!