Is there a drainage hole in the bottom of the container it's in? If there is then really water that sucker, deeply so it really flows out of the bottom drainage hole. You might have to water like this once a week or so depending upon temperature. They grow on the dry side.
But they produce deep roots in a container and if you are essentially sprinkling a little water on top, the plant could be too dry causing the leaf curl.
Also in a container that size, try putting a tbsp. Of slow release plant food on the top of the soil 3X a year.
