Light sensor problem

[lvlonkey]

I've noticed lately that randomly my light sensor will stop working and give a lux reading of 0. Resetting the phone will make it work again. Any idea why this is happening? Is there a way to reset the sensor itself without resetting the phone? I'm on 7.0 June patch. I was using f.lux and I initially thought it was that so I disabled it and it still happens.