Fading phal flowers?

[greenpassion]

This is really odd. Earlier this evening I posted here about a particular phal of mine that is developing fading flowers. I can't find that post anywhere. Odd. So I 'll have to write it all out again apparently.
One of my phals (I have 27) is one that I've had for around 4 years. She routinely throws up branching double spikes with beautiful peach flowers. She stays in bloom for 5 to 6 months. That said, I noticed the other day that her flowers look sort of washed out. Conversely she's also still putting out buds and they are opening as usual. The new flowers from these latest buds are rich in color, while, as I mentioned, the older ones are faded looking. Has anyone ever had this issue? This phal is extremely healthy, growing new leaves and roots all the while spiking and blooming. Just wondering what's up...??