OEM Xenon headlight bulbs are 4300K bulbs. The more you use the headlights, the temperature rating goes up. At the end of Xenon bulbs' lifespan, they are operating at around 4800K. So basically, as your headlight bulbs get older, they become MORE blue/purple and naturally, both headlight bulbs age together as they operate together.
Everymay and airlordz, have either of you recently (or not, depending on how long you've noticed this Xenon weirdness) had one of your Xenon headlight bulbs replaced? Also, is the illumination onto the road the same from both bulbs?