Fungus/Heat Stress on Masdevallia Herradurae?

[RaN]

Howzit. Sunken yellowish spots have been appearing on the undersides of this Masdevallia Herradurae and also on a Dracula Lotax that was next to it. There are also darker brown to black spots as well.
I have had the plants for 3 weeks and they came to me a little weathered but still very healthy. These two plants are grown outside under a covered walkway, facing a westward direction. They do receive some direct sunlight after 2-3 pm but only for a couple of hours before the light is filtered through some trees. Temps here range from very low 80s/high 70s in the day and may drop down to mid 50s/low 60s at night. Some nights are cooler depending on sun or rain during the day. It does rain often here. I live at 2700 ft level or so. Both plants are putting out new growth and possible inflorescence. The pics show the sunken areas and spotting on the Masd. in red circles and new growth in green. Could these spots be fungal? Heat stress? Any help will be appreciated.