This should answer everyones question...my rabbits do the same..lotsa times if I come out at night dumbo freaks out and starts running around the house..
"Rabbits' eyes are adapted to being able to see moderately well in half-light conditions rather than extremely well in either light or dark. This is because they are crepuscular, that is, preferring to be active at dawn and dusk, when natural light is dim. But unlike the eyes of other animals who can see in muted light but who also have enhanced night vision, rabbits' eyes have no tapetum, that is, the structure that acts to amplify light that has entered the eye. And so they cannot see well at night. In consequence of these factors, your rabbit's view of you is likely to be "grainy," and he will recognize you by your shape and manner of movement rather than, say, the details of your face. If you enter the room carrying something large enough to alter your shape, your bunny most likely will not recognize you and will be afraid. "