Command created blocks update light level?
Solution 1:
This is a common bug that happens to me all the time.
I have a few way of fixing these:
Firstly, placing blocks (in particluar light emitting blocks) around the glitched light patches should fix the problem.
Secondly, if placing blocks doesn't work, try reloading minecraft and the world. Another thing I have found useful is to set your render distance to 2, then press back to game... and then put your render distance back up to 10-16 to fix.
Thirdly, if that doesn't work you can use McEdit to fix the glitched light blocks