What I expected to happen was..:
The comparator power source indication light to turn off when the power source was taken away

What actually happen was...:
The comparator power source indication light stayed on when the power source was taken away

Steps to reproduce:
1. place a comparator
2. put the comparator on subtraction mode
3. place redstone on the output side of the comparator
4. place redstone on to the left of that redstone
5. place redstone on to the left of that redstone again
6. place redstone towards you next to that redstone
7. have a redstone repeater getting signal from the last placed redstone going into the side of the redstone comparator