That would be my guess. The Vertical and Horizontal image/screen adjustments are what you are looking for in your TV's menu options.
Usually you wil have 4 options.
Shift up/down
Shift left/right
Expand up and down at the same time
Expand left and right at the same time
Either Shift up or Expand up and down at the same time.
I get Closed Captioning data sparkle lines on the top of my Vizio
LCD HDTV sometimes.