The last few days I've noticed that the L2 button on my ps3 controller is stuck(sort of). While playing certain games the L2 button seems to rapidly toggle itself on and off. I first noticed when I was playing Battlefield 3, I was playing Squad Death Match and whenever I respawned the controller would throw a grenade by itselft. Then I was playing Metal Gear Solid HD Collection. Whenever I would walk the L2 (Item Menu) button would seem to just press itself and release itself atleast once a second. When I stood perfectly still this would not happen. I can play games like MW2 and MW3 without this problem, But I was just now playing GTA IV: Complete Edition and while walking around with a weapon equipped the controller toggles the L2 (Aim) Button by itself. I can't walk because my controller is rapidly pressing L2 and then releasing it, its making playing some of my games unbearable.

Is this something I can fix myself or should I take the controller back with the receipt. I bought the PS3 in March 2011.

you can try resetting the controller . look on the rear at the top , there is a small hole
press a pin in the hole to push a reset button inside

reset and sync to the ps3 again , good luck

you cannot return the controller , it is warrantied for 30 days from the purchase date , and if it failed in that time you would have to send it to Sony , not the store you bought the ps3 from
controllers wear out because they get used a lot , or get wet or dirty , when they do you replace them , simple enough
if resetting it doesn't help then you have to buy a new one

if you have not bought an extended warranty for the ps3 then you have until one year from the original purchase date , you can buy an extended warranty in the playstation store
this will cover the console only , not the cables or controllers , and can be purchased for one or two years more coverage if your ps3 is less than 1 year old and you have the original receipt