What I did: I placed a torch on a block of redstone ore while in a dark cave and then removed the torch from the redstone ore block and the lighting did not reduce to the level that would be expected if I had just tapped the redstone ore block.
What I expected to happen: I expected placing the torch to light up the room (which it did) and I expected the room to go darker when I removed the torch (but it didn't, instead it stayed the same full torch brightness for the duration of the redstone illumination). I expected the level of light to reduce to either the level associated with just tapping the redstone ore block or to complete dark if placing a torch on the redstone ore block doesn't count as a light activating event.
How to reproduce: Open a creative world, enclose yourself in a hole with a redstone ore block. Tap the redstone ore block to observe that level of lighting. You can wait for the light to go out, or not. Place a torch on the redstone ore block and observe the brighter level of lighting. This is all normal so far. Now remove the torch and notice that the lighting does not go down (as I thought it should) to the duller illuminated redstone ore block level, or to the full dark level).
This might "work as intended" but if so, that's news to me.