I'd have to agree that Lexus paints sux! I have so many chips on the front of my car... you really can't avoid them even if you're driving carefully on the highway (keeping a safe distance from cars in front of you). And yes, the chips can go right down to the metal, therefore turning orange from the rust. Your touch-up paint pen is your friend
If your paint is relatively new, it's worth it to get the clear protectors (ie. 3M) over it to prevent most of the "bad ones". These protectors may turn yellowish after time though (or so I've heard). If you're gonna do it, don't forget to do your headlights too.