iPhone 4 turning off in pocket

So I've had this phone scence July and just last week out of the blue I was in a call and my phone turned off and it took me a long tine to get it to work . Even resting it didn't work or connecting it to the computer. Anyway I found out the if I press on the top right corner of the screen glass it would turn off and sometimes if it wouldn't turn off I would have to put pressure on it and move the screen or tap the corners Then try to turnturn it on. Has any had anything like this happen?