iPad Multitouch

Hi,

I live in the UK but I got my iPad from the USA and I notice that if you put two fingers on the screen at the same time when using, let's say, Pianist Pro, it takes a second or two to recognise the input. Earlier today, I decided to test it out on one of the iPads in the London Apple store and when I do the exact same thing on the same app, it recognises the input straight away. Could this be a defect on my iPad or is it something else, I would really like to know?

Thanks
Leon