If you are referring to the lighter green centers of the plant in your picture above, new leaves are lighter green. They will turn darker in a few months time. I think your plant looks very healthy.

Thanks for that. I was thinking it was turning yellow from over watering. I put about 500 mL every 2 weeks or so into the pot.

I don't think so, the new leaves are lighter and they darken up as they age, I just bet that by Sept. those new leaves will be the same color as the rest of them. I think this is very normal. It may darken up if in the shade, but I don't think this is the best for the plant. Norma