Dendrobium Phalaenopsis- sunken rings on the underside of old leaf

[snoozy]

Hi!
My first orchid- a dendrobium phalaenopsis type- is sick Sunken rings have appeared on the underside of an old leaf, at the base!
It has beautiful roots with green tips, and is putting out a new growth! Even bloomed for me this year...

Spots:
Attachments 1 and 2

Roots and new growth:
Attachments 3 and 4

It enjoys warm to hot temperature throughout the year.
Sits on a southern veranda, receives bright indirect sunlight!

Are all symptoms indicative of virus? Are there any other possibilities?

Thank you for your time!