Hey all, I have a 7' tall guy named Mike. He currently lives in the hallway where he has access to (early) morning sun but I'm worried he's getting too cold out there. Though indoors (apartment building) it's not heated. Anyway, I noticed some weird small dots on edges of his leaves in the last week or so. It has started to show up on many of the leaves on the left tallest branch, but none on the right branch yet. Is this some kind of fungus or disease? They aren't sitting flat on the surface, seem to be coming from within the leaf. Nothing on the back side of the leaves.

How should I help him? Thanks in advance! Photos attached.