Q: why does my iphone keep falling off tables?

no

An iPhone won't slide off by itself. Something is causing it; the vibrator, a pet, someone walking by and brushing it, a poltergeist, something. I'd suggest you not leave it on a slick surface.

Regards.

Never seen this on mine either. I leave it on the edge of my kitchen counter, my bedside nightstand and my coffee table frequently and never had it move on its own and fall off.

My iPad does this from my bedside table, possibly something to do with static?? I leave it face down on a pile of paper .. although no one else seems to have this problem?!