Why is my monitor doing this?

I have a 17" Samsung computer monitor. Recently I noticed a faint horizontal line will move from the bottom to the top of the screen. It doesnt do this all the time, and only till not long ago did this start. It’s only between 1-2 years old. Any ideas why this is happening?

Might be a magnetic source nearby? A speaker perhaps? Maybe you have some electrical product sitting next to the monitor?

This did happen to me once, I called the electric company about it & turned out they had to come out & reground the electrical boxes.