thin red line on Hitachi plasma?

I have a Hitachi 42PD5200 plasma that has developed a thin red line about 4 inches from the left hand side of the screen. There is another one at the extreme edge on the same side but this does not really affect viewing. The line is at the same position as the left hand edge of the picture if you are viewing non widescreen. I have checked all user settings but it is still there. Any suggestions would be appreciated.