Ipod nano 3rd generation menu button not working well

My ipod nano 3rd generation menu button is not working well. I have to always press it really hard for it to work. I bought the ipod in early January and the problem started to occur around April. I don't if apple can do anything about. Would they give me my money back, fix it for me or get me a new one. I don't care which one they choose. I want to know what i should do with the ipod. Take it to the apple store,mail it in e.t.c.I still have warranty on it. This might not seem like a big problem but what if it freezes and i press the menu button and center button and it is not working.