I just ran into this myself. It's not an issue of iOS, as Jonathon Stark's test page worked perfectly fine. I found it was an issue of a library I'm using: energizejs
I created an issue for it: https://github.com/davidcalhoun/energize.js/issues/15 And also created a jsfiddle to prove the issue (linked on github)
Not sure if you're using that or not, but it's likely some piece of code you have is mucking with it.