HID from the internet:
"Xenon headlights provide a beautiful white light which may have a cold bluish tinge. But what if is suddenly takes on a violet glow or even pink? The answer is simple – it has come to the end of its life. Unlike incandescent lamps, xenon lamps do not suddenly burn out. It’s more of a gradual process that involves a considerable loss of light output and a color shift. HID lamps have a lifespan of approximately 2000 hours."
New bulb for sure! I've often found it's best to replace Xenons in pairs as the other wont be that far behind. Xenons lose brightness over time and having both new at the same time will probably be a big jump in brightness for you!
Mine failed in a different way, but both failed at almost the exact same time. One started to flicker, then it just quit. The next day, the other one just quit. I was a bit worried so I took it in and the dealer checked the ballasts and wiring, all good. The only problem was the bulbs were $135 each, but labor was only 15 minutes. They installed one wrong, and it was aimed off in people's front yards, but a quick return trip and they performed a headlight alignment procedure, which solved it to this day.
Note: The owners manual recommends taking it to a shop for this, which is exactly what I did and I'm glad I did because the realignment was free.