That's the HDR adjusting to the change in light, as I'm sure you know. It doesn't really differentiate much between surfaces when there's enough light (or lack of light surrounding the character position, which is the achilles heel of HDR) unfortunately, and it is a little bright in general. I think it's good though. I've never seen a game that did HDR and metal-flash properly, as opposed to just dousing everything in a blurry orange glow ala Oblivion.