Yeah, Sneek is right - she´s stretching for the light. Looking at your image where the light is on, you can cut that distance in half. Also, it looks like your using both veg and bloom? Using bloom will do nothing, but to add extra light stress to your plant at this point.
If you are using the fan, point it away from the plant - just enough to have the seedling move a little bit from side to side. The plant will respond by hardening up the stem.
Nice setup by the way 👍👍