I found the cause. It's a 4.2 development that hides the USB debugger by
"Android 4.2 and higher, the Developer options screen is hidden by
default. To make it available, go to Settings > About phone and tap Build
number seven times. Return to the previous screen to find Developer
options." - Found at: http://developer.android.com/tools/index.html
At least now it should appear in search results more easily!