Stumped. Not sure if its too early to tell...

I have read and read multiple threads and forums ICMAG, RIU, GC, Jorge, Rosenthal, etc.
Two separate plants, two separate problems.
Plants are healthy aside from the minor issues shown in the pictures. Would like to keep them minor issues.
One is showing a browning/rust color between veins on foliage. Only on two of the bigger fan leaves and was recognized today. Not sure if its too early to tell exactly what it is. I have a couple of ideas, but still not exactly sure what's wrong. This has not taken over this plant, yet. I would love to keep it that way.

This is the other plant. Only a single leaf with this issue thus far. Leaf was at bottom of plant.
It started as yellowing at the tip and eventually progressed to brownish/rust color. Again I have a few ideas but was wondering if anyone has had similar deficiency/toxicity issues that resemble these.


Both are grown in soil with organic nutes from distilled water. Heat and humidity are not a problem(75-79 degrees and 50-55rh).
Any help whatsoever would be greatly appreciated. Just looking to be pointed in the right direction.

Thanks.

Apparently everyone is as stumped as I am. I'll keep this thread updated when I figure what's going on. Hopefully it can help people with similar problems.