Yellowing Spike As Flowers Fade?

[vlhart]

Hi guys--

Question about phalenopsis spikes. I have many phals now and typically when they're done flowering the spikes slowly fade from green and dry up/or I cut them back.

But I've had a few (admittedly less healthy ones, typically right from the store) where the spike goes yellow in a day or so starting at the flowers and going down to the plant. Is this simply a shock/adjusting to new environment situation or something more specific? Or is it normal?

And is it a good idea to cut the spike back immediately when it starts going yellow/orange?

Thanks!