Dont worry, It's normal - Was the message I got back from Acer - Esplex when I told them I thought my screen was playing up. Apparantly its common after work has been carried out on the screen.
I Think they're bored of me, my laptop has been repaired 3 times now by them, and they seem to refuse to repair it again
So yeah.. When I open my laptop or adjust the monitor, its supposed to do this.... I shouldn't worry about the screen having a dodgy conection... Its normal..
Don't get an Acer, ever.