Just wanted you to know, should anything happen that changes the color of the blooms in the future...
Naturally speaking, there are currently no such things as naturally occurring true blue Phals. If the ones you have are true blue, or aqua blue, those are not the flower's natural pigments. The flowers are most likely dyed that color.
So if it does end up reverting back to its natural pigmentation (whatever they may be), the flower's color change doesn't necessarily mean there's anything wrong with the plant.
Just a heads up.