Yes—it may seem a bit weird, but it’s completely normal.  Purple is the opposite color of green for the human visual system.  Our retina contain red, blue and green color photoreceptors.  The green cones become saturated by the green light of NorbRELIEF, so momentarily only the combination of red and blue cones are able to be activated until the pigments get recycled by the green photoreceptor cones.  It only takes a few minutes for this to go back to normal for most people (without retinal disease).