Do Apple Studio Display bulbs turn yellow?

[mectojic]

Just got a second 17-inch Studio Display, I love the aesthetic and tall real estate of these.
I realised that they have quite different coloured light indicator bulbs.
Is this a case of some decaying over time, or did Apple actively change the colour, eg between the Digital Audio/Quicksilver transition?
(Strangely, the white light looks more orange through the camera, so the photo doesn’t really represent the difference well.)

 

[bkmoore773]

Older LCD displays are back-lighted with a fluorescent tube. I'm no tube expert, but I've noticed that if an LCD (with fluorescent tube) sits in storage for an extended period of time, it can be slightly yellow when first turned on. The yellow tends to fade back to white with extended use. This is just my observation. You can compensate for the yellowing in the display profile settings under OS X.

 

[Nermal]

The indicator light isn't "powered" by the LCD though, so any yellowing there isn't going to affect it.