I bought this beautiful plant home earlier this year and it has been growing like crazy. Within the last week I noticed that the edges of the newer leaves have yellow spots. The plant is still giving new leaves. I water 2 to 3 times a week depending on how dry it is. The humidity level in the house stays around 55 and I mist the leaves every day. I watered it three days ago and today the top few inches is dry and the moisture meter says it's at the edge of dry so I don't think it's over watering.
I suspect it might need some fertilizer. Some Epsom salt would be good too. Dissolve a tablespoon of Epsom salt in a gallon of water. If that's you're only plant, obviously scale down the amount. If you have several plants though, you could give them all a shot of Epsom salt. It provides magnesium.
I was thinking about it but since I just repotted it in May I didn't think it would be necessary yet. 
