elmo

So I just got my 2012 3days ago and noticed that when in 4th gear the car makes a whining noise but in all other gears it is quite . Friend of mines is telling me to wait till I hit 500miles as I only got about 200 , but just curious if any one else had this problem when the got there car ?? If this is normal and goes away or should I shoot back to the dealer asap ??? Thank you