I have my Galaxy S4 connected with my PC and ran the "Building My First App" tutorial from http://developer.android.com/ . There were no problems, but I noticed many messages about the LightSensor in the LogCat view in Eclipse, like these:
09-17 17:41:24.781: E/LightSensor(736): Light old sensor_state 0, new sensor_state : 128 en : 1 09-17 17:41:25.152: E/LightSensor(736): Light old sensor_state 128, new sensor_state : 0 en : 0
I found several occurrences of the string "Light old sensor_state 0..." on the web. So others get this type of messages, too (where a phone was mentioned it seemed also to be a Galaxy S4). But the posts/questions/answers were always about something else. It looks as if everybody ignores this kind of messages as noise.
I played around a bit and noticed this: As long as the phone is active those messages do not appear. But when I switch it off, the messages appear about every 10s. Does anybody know what they mean?