I don't have a 4900, but I have noticed it on my 301. Infact as long as I have had my 301 I have always noticed it even more on channels that are live IE ESPN FOX NEWS CNN etc. I don't notice it so much on say TNT or TBS unless it is a live show such as Basketball or football. I have had the local dealer out here quite a few times and it does not do it when he is here so we can't really track the problem down. I hope when I upgrade to the 510 that it will go away. CC