The difference between regular bulbs and led's is if the circuit has any power feed at all, the led's will glow where the regular bulbs won't. Same thing happens for the trunk light in my Challenger. I usually shut the lock during shows and after a minute or so the led trunk light is barely lite. There's some kind of phantom feed from somewhere.
To avoid the minor "glow" you will want to go with a CAN Bus LED. Even though they power is "off," there is still a minute current to the bulb. LED's take a very small amount of current to come on. The CAN BUS bulbs will turn off completely. AND, the fade out will work with them.