Distance wise the lights look fine, just make sure the lights never touch the plant and keep them about 1 to 2 inches away from the tips of the plants. good luck:thumbsup:

Edit: i cant tell by the picture but it looks like there isn't a reflector above those lights, this means your plants wont be getting all the light your providing and it looks like its causing them to bend more towards the light then usual (somebody please correct me if I'm wrong). to fix this get either a metal reflector or just paint the box with a flat white paint.