I found out the other night that my stock fog lights weren't working, so I pulled the fuse and looked at it put it back in a couple of times. The fuse looked good, so I dug out my muti-meter and started to trace the problem. After messing with the fuse a couple more times, the lights came on. I didn't do anything to fix the problem other than reseating the fuse several times.
Could that be a warning sign of a possible electrical problem or just some oxidation on the fuse?