As you can see there is a very dark area in front of where i'm standing at light 15, usually its just a visual glitch but this these are not visual! As you can see in the next picture its light level 3 when i stand there, but as i update the block it turns to the regular light level (image 3).
I've added an additional image (image 4) to show what these look like.

Ill i did to update the light was place and break a torch, i did not affect anything else in the area.