Pleurothallis velaticaulis mottled leaves

[Polarizeme]

The leaves on these plants have a mottled appearance. Is this normal? They don't turn colors, no brown or black. The leaves just look mottled, green and light green. The newer growth, since adding shade cloth in the greenhouse, appears to be more uniform in color. I thought maybe it was from too much sun and then shading them or possibly a nutritional deficiency? They don't seem unhealthy otherwise and they bloomed for me earlier this summer.



New growth