I just hung my Samsung PN58B560 and have not noticed anything like this. Also none of my LCDs exhibit this problem or even my lone LED/LCD.
Infact, I just went and checked, and saw zip, zero, nada line bleed with menus, sports, HDTV or BD on my 58B560 plasma. The pq is crisp and very clear. I am leaning towards a household wiring issue or a ground loop hum with many of these affected sets. That was my first impression and I am sticking to it. I know firsthand how older or improperly installed wiring, and grounding, will really mess with electronics.