Strange 'current' sensation felt when charging iPad using wall charger

Tried charging my iPad using the wall charger today. When plugged in, the aluminium parts of the iPad give off a slight tingling sensation.

I've had this before in other aluminum devices like my old iPod Mini, just wondering if this is common (and safe) or if there's anything I can do to alleviate the problem.

My mains plug is new and has no earthing problems and I'm using the iPad charger that is meant for my market, its a 3 pin plug but not sure if the earth plug is a dummy plug.

Has anyone used a multimeter to check the iPad for current leakage before when plugged in? I seem to see these sort of posts for some of the Al shelled products.

Any assistance would be appreciated! Thanks!