Yellow Leaves on Niraporn Baby Snow

[Cubazuelen]

I have had this plant for almost a month now. During the last week i have noticed a yellowing of some of its upper leaves. If these were leaves lower on the stalk i would not be concerned, since they are further up I feel I may have a problem. It has been in bloom the whole time I have had it and is dropping its bloom now, but there are 2 healthy buds that look like they will open. I water every 2-3 days and fertilize weakly every 2 weeks. It is in a south east facing. Any help or advice would be greatly appreciated. Thanks!