Electricity passes throug the MacBook to me
So, I was charging my MacBook air, its fairly warm, I touch my iMac, I notice my pinky feels tingly. I think its my iMac, freak out, touch it again to no avail. I then proceed to keep my MacBook air on my lap, and type on my apple wired keyboard connected to my iMac via a USB hub that is plugged into the wall. I feel the charge again and I realize the current is coming from my MacBook air.
Should I be worried? Because my iMac and my aluminum keyboard is "grounded" (well the socket this is all plugged into is not grounded... the house is old) and current goes through, does that mean that its the positive line that's live? because if it was neutral or ground it wouldn't go through... And how, if I should, should I approach this to apple?
EDIT: I just put my pinky on a screw on a light switch (So that's definitely grounded) and I definitely feel a current.
EDIT: The plug I was plugging into's ground is not actually grounded.