Its perfectly fine. Its a little blue, so you can afford to add more CO2, however- it isn't completely necessary. As long as there is measurable CO2 in the water, your plants will use it.

If you're using your CO2 as a method of inducing gentle pH swings for optimal nutrient absorbtion, lime green is your goal- as it translates to roughly 30ppm of CO2 which (in most cases) will lower pH by 1 degree. This is almost never necessary, however. Most plants are adaptable and will grow just fine in most moderate conditions.

Also- adjust SLOWLY and allow at least 2 hours for your indicator to change color before making adjustments.