That's normal. I think the makeup of the screen may naturally cause this if light is shining on the panel. Usually the picture is bright enough behind the panel to dampen those effects, but I wouldn't consider light refraction off of the UltraClear Panel out of the ordinary.
I noticed that whenever lighting (i.e. sunlight, house lighting, etc. is reflected off of the screen on my B750 that it gives off a rainbow like reflection. Really noticed it this morning when the morning sunlight was shining on the screen while the set was off. Is this normal or is there something on the screen that is causing this? It doesn't seem to affect the picture quality and is only noticeable when set is off and reflecting sunlight or house lighting.