I too had a problem with a pale green N. Madagascarensis and I applied a very
weak foliar fertilizer spray as it appeared to have a nutrient deficiency.
If it is the same condition the leaves will be mottled also. In particular
I used an African Violet formula 7-7-7 liquid with micronutrients and
diluted accordingly. Do not let your plant see the label as it will cause it
distress.
Thanks !
Joe