My iPhone 4S will be playing music and then it will stop and go into dock connector mode. What I to stop this

Hi, my iPhone 4S will be playing music or nothing and it will randomly stop! I doesn't even show the volume bar. It goes right into

dock connector mode when it's not even on a dock. It only does this when I want to play music through the iPhone speaker. I

don't know what to do or how to fix this, It started doing this when I was on 5.0.1 and I read something saying it would help

to upgrade my phone, so I went to 5.1 and nothing was fixed, sometimes it does this and than it doesn't. For me to get it back to

normal I need to hold down the Siri button and select the way I want it to play when the device button comes up and it says

" iPhone " , " iPhone Speaker " and sometime it won't even say those. Will apple give me a new phone if I take it in? I never signed up

for Apple care. I just got this phone in February 2012. PLEASE HELP ME.