http://www.youtube.com/watch?v=e7LjRQ2PeKM
Here's a video of it, the quality is poor but it still demonstrates what I'm talking about.
The pipboy light seems to fail to cast on terrain like this sometimes, and it seems only to be terrain, objects show light properly even if the glitch is happening on terrain between the light and the object. I'm mostly curious if anyone else even has this glitch, but I am hopeful someone has experienced and solved this problem before me.
FYI I have windows 7 64bit, a Nvidia 450 GTS with the latest drivers.