scroll up/down will fire swipeleft/right event?

scroll up/down will fire swipeleft/right event?

Hi every,
  I met a problem, in my app I bind swipe event on my page and the page is a scrollable one, when I swipeleft/right it works find, but sometimes when I try to scrollup/down my page the swipe events fired as well(I'm sure I just scroll down/top and I only tested it in iPhone iOS5), I don't know why, any ideas?