Yes, I have had some unusual vanda leaf loss this spring as well, and root loss too. The leaf loss started in the winter and probably the root loss too. I believe the colder winter and very dry air is the culprit in my case. Even in the garage it got into the 40s at night here - and very dry air. My leaf loss had stopped since I moved them outdoors except for one sickly vanda I still hope to save. Please check as Bruce said for bugs and check the roots, and post pics. Good luck!

Tami