Today, I swapped the original license plate lights on my 2012 Prius v to some VLEDs for a brighter whiter light. And I was very surprised to find scorch marks on the bottom edge of both bulb housings. The bulbs themselves look fine, and no other marks besides on the bulb housing. I used to just turn on my lights all the time since the v doesn't have daytime running lights. I'm thinking that might be the cause. Though I was under the impression that having the lights on any time would only potentially shorten the life of the bulbs, not this.
Look like the LED bulb is getting too hot. Use the originals, besides too bright in the back might be illegal in some states.
Its not really a problem unless there's signs of melting or the metal parts are scored/scorched. I don't see anything but discoloration, which may be expected. Those things are designed to be hot and the material stands up to it. rjparker is right though, the LEDs could get even hotter.
That is from the original bulbs, I just changed to LEDs today. The lights arn't blindingly bright especially on a black car. The heat from the LEDs is one of my concers after seeing this from the original bulbs. Though there is a nice heatsink on the top/back portion of the LED, and more importantly, my wife is now driving the car and generally doesn't use the lights during the day. No signs of the metal scorched or actual melted plastic.
An impetus to get DRLs? Especially on a dark car in the dawn and dusk hours they are nice to have. I like DRL's because they don't require the rear lights to be on and someone behind to figure out if the lights he sees are running lights or did I just put on my brakes. A split second delay in figuring that out could cost us both. I want max contrast.