I'm a novice mac user, about 1 yr, and just noticed, quite by accident that the perimeter of my IMac screen is magnetic. I was trying to put my earbuds away and they got close to the edge of the screen, the black band around, and they stuck to it. Got out one of my daughter's cheap bracelets and it hung on the screen. I'm from the pc world and can't find a mention of this "attribute" in the user's manual. Is this normal? Please and thank you.