I have not seen this mentioned but I have trouble with it every day. When I make a call the proximity sensor does not always work. During the call my cheek will pull up the keypad and then start dialing. Sometimes this will happen even if I remember to hit the sleep/wake button as I start the call (to turn off the screen). Very embarrassing to explain to the other party why your phone is touch-toning over their conversation. Does this happen to everyone or just me? It did it with the I4 and now the K4 firmware.