Based on 9to5Mac's article here, it appears that "The iPhone 4S has a neurotic tendency of always wondering how close your face is. As long as the screen is activated, that IR sensor will be shining brightly. Siri is ready and waiting to answer her masters beck and call at any time. So whenever the screen is active, the proximity sensor is active too. Thus, whenever you raise the iPhone 4S to your face, Siri is ready to take orders." I've since then disabled the raise to speak function of Siri. I'm just OCD about having something always on that I don't actually use. Didn't like how they described "shining brightly" and "at any time" seems like this would use more battery. I don't think it uses that much battery, but since I don't use the feature, I'll turn it off anyways. Just sharing this to those that are in the same boat. You can disable the raise to speak by going into Settings -> General - > Siri.