Haze, many corals will give little hints that something has changed or is wrong. Many soft corals (including mushrooms) will react to reduced lighting by expanding their surface area and/or reaching light. Kip and Mike are absolutely correct that this could be something worth looking at if it continues. Lights do wear out and as they do the spectrum and intensity changes. It's hard for a person to notice - but your corals do. It's good that your paying attention to them, they'll tell you how their doing as long as you don't ignore the signs.