Take on the touch screen that touches back

What the hell was that???
It felt like somebody just stuck my tongue on a battery except instead of my tongue it was my finger and instead of a battery it was my IPhone
You know how you get that weird fly-zapper buzz when you touch the screen of a tube TV well that is what it feels like when I sometimes go to search for an app. Now this has always been some issue with a TV although I think it has not been as much of a problem with LCD screens although I don't routinely put my hands on my 42 incher reserving that for my 8 incher. But there are times when I use my IPhone and it feels like I have to penetrate some kind of forcefield and somehow it just doesn't feel 'right'
It doesn't happened all the time but when it does it seems like the electronic equivalent of getting zapped when bra ing a door handle after walking over a carpeted floor but every time it does happened I am left to wonder if I'm sucking in just a bit of finger cancer