Flickering dashes across my screen...

A flickering line of dashes started showing up on my screen, what gives? I have a MacBook OSX 10.9.5, 2.4 GHz intel Core 2 Duo, 4 GB memory. The flickering dashed line is 2-4 inches in length, and shows up anywhere on the screen. Is the screen going bad? It just started in the last couple of days, first noticed it when I was playing SUDOKU online.