Hmm, weird I know. My D. rotundifolia did much the same a month
or two ago - it had been white flowering, all the specimens outdoors
remain white-flowering, but in one of my terrariums... they came
out pink.
I still can't quite figure it; must get the tray water analysed.
Seven years seems like a long time between colour-switches - have
you noticed any different circumstances this year? - particularly
I suspect algal/bacterial action in my own case altering the
water chemistry in the affected tray - or any noticeable stress
from irregular water, light, temperature etc.?
There certainly seems to be a phenomenon of sorts here, and not
only in cultivation. Any thoughts since last time Fernando?
Happy growing,
Peter