Noticed it via HDMI on all resolutions but not tried the same material on Scart ever.
There are other issues with the set though like lots of faint sparklies over the screen(qorse in darker parts). Again very noticeable in HD not on SKY via scart as shades seemed quite crushed in comparison.
I get shadows of gridlines as well on Sky, Wii and PS3 on all cables.
I hope the panel is not damaged and its maybe the inputs.