Panasonic Plasma Flat screen TV issue???

I just got a 50 inch plasma flat screen TV 8 weeks ago (only been used now for 4 weeks) and today it started having lil lines across it (static looking lines) & the screen jumps slightly. I called the store I bought it from & if not for my extended warr. I bought, I'd be outta luck. The mgr was shocked that the TV was doing this, especially cuz it's Panasonic. What would make a TV do this??
George : the stinkin store told me that cuz it is after 30 days, I have to use the warr. I bought. If I did not buy that warr. I would be stuck w/the TV the way it is............CRAZY, right. This is Circuit City too!!!!
EDIT:addL info: THANK YOU 4 helping!!
Model No: TH-50PX75U
Just started doing this - only had TV for 4 weeks- Bought brand new
I was watching a DVD when it first started. I thought my DVD player was going bad, so I then turned that off & put the input back to my satellite TV(directv) & it still did it. The lines are whitish colored & move around. Kinda like when there is interferance with another object. Also the picture on the screen was slightly jumping. I mean, like rapidly moving a quarter inch up & down occasionally. But the white lines that looked like static ran across the screen in random locations. We have it plugged into a really expensive surge prot. We also checked all the cables again (HDMI) to be sure we were still attached & all was good. It did this on all channels. What is strange is I was scheduling for the warr. co. to send the service guy out & the next day, the TV did not do this. It has been fine the past 2 days.
I am afraid however, it's the start to a problem we may encounter down the road. Any help or thoughts you have are appreciated!! Thanks a bunch!! =)