IPhone 4S skips/restarts song when open app or phone?

I just bought a new unlocked iPhone 4S from the apple store and it's plastic wrap is still on the screen and everything and I've noticed a few problems with it. So when I play music and unlock my phone or open an app while the music is playing the song will skip or restart or rewind, should I take it in to the apple store or can this be fixed? Also I've noticed that whenever I make phone calls the in call volume is almost inaudible, is this because the plastic screen is still on the phone or is my phone faulty? I've tried turning the volume up all the way. Is there anything I can do to fix these things?

I have had this issue on occasion. Usually simply turning the phone off (slide to power off) giving it at least 1 minute and turning it back on will help. If that doesn;t work reset the phone.

You turn the phone off by holding down the power button. Reset by holding down the power and home buttons at the same time for 10 seconds and letting go when the screen goes blank.