It is normal because of the illumination. Usually the color of the eyes will not change which is determined by the genetic genes. Only when you have the problems at the body health can you have the change in the color of the eyes. If you are still worried, you could go to the hospital to have a check on the eyes color.
Human being's eyes will turn a little lighter under some circumstance follow the health condition or light condition of environment. It's normal, especially the westerners as their eyes are lighter than Asian people. But some people's eyes will turn lighter if the eyes get inflammation or pink eyes or other eyes disease, so hard to say if your eyes have problems. If your eyes are feel nothing unease with the well vision. I guess it is only the circumstance affect by light reflection. But if you feel dry eyes, red eyes or itch or any other discomfort in your eyes, you must go to hospital for the details check.
This is maybe just a normal phenomenon in the visual sense. When your eyes are looking at light, or when a light beam enter into your eyes, part of the light is absorbed by the eyes, and part of the light is reflected out. In such condition, your eyes may appear a lighter color because of the light the eyes adsorb. But in fact, your eye color does not change at all. This is just a kind of optical phenomenon which you do not have to worry about. However, you should not usually let light directly shoot into your eyes in case that there are ultraviolet rays or infrared rays which can do harm to your eyes.