A forest of Dark Oak Trees burned down by lava in a Roofed Forest biome, and at night time I noticed floating 14 light level blocks in the air, upon placing a block on these light sources the light level vanishes. This problem has caused about 50 air blocks to have a mysterious high light value. I have also had this problem in the nether and believe it is a problem with fire being invisible and not going out, possibly because of leaving the chunk while it is burning.