You may just need to adjust the cable length. Just a quarter turn of the barrel adjuster at the lever or the one at the derailleur might do the trick (actually changing the effective cable housing length but with the same result, longer housing = shorter cable and vice versa). Might save you a trip to the shop and improve your ride sooner. If the derailleur is hesitant to go into a bigger gear (smaller cog) turn barrel adjuster counter clockwise. If shifting to an easier gear is problematic, try turning clockwise. If this doesn't help, it's easy to turn them back to where they are now.
Congrats on the new bike!