Vanda hybrids with Asctm ampullaceum or christensonianum (now V. ampullacea & christensoniana) in the background often do this when grown in high light. It is normal, and harmless.
__________________ Kim (Fair Orchids)
Founder of SPCOP (Society to Prevention of Cruelty to Orchid People), with the goal of barring the taxonomists from tinkering with established genera!
I am neither a 'lumper' nor a 'splitter', but I refuse to re-write millions of labels.