Tail Light doesn't turn on initially

Hey guys I'm confused. I drive an 08 Aveo5 special value. The top light on my right tail light, sometimes both, doesn't turn on when I start the car. But by the time I get home from work at night (about 15 minutes) their both on. Is that a sign that they're going out or is it wiring or maybe a fuse? Any help appreciated. Thanks in advance

It's a sign alright. It's a sign indicated your going to pull your hair out chasing down the problem.

1) Replace the bulb. As things heat up, sometimes it will make contact or not.
2) Pull the assembly out and check the wiring to the light.