Let's wait for the experts to chime in
Maybe this is an expected behavior for the new canes..
I'm kinda worried about my Den Phal too ('Polar Fire'). It looked stressed under lights but now it's probably not getting enough "sun"...
Btw, I thought keiki production was provoked by disturbances in the "rest" period (watering, temperature), and not the growing season events.. Hmm... found this article (painful to read - white on black, but looks interesting)..
www.ricardogupi.blogspot.com/2012/11/dendrobium-keiki-what-causes-them-to.html