I've seen this on the login pages for both Google and Facebook. I click the username field to open up the VKB, and then enter my user name, then I click the password field to enter my password, and then I tap the login button, but that gets mapped to the wrong element, and usually a link below the login button gets tapped as the VKB is being closed down.
my reading is that this is only when the VKB is appearing or disappearing, which is minor enough that it is a minus.
Well, it will happen on a lot of sites when you try to log into them I think. Specifically, when you try to click something on the page (presumably the Login button, or maybe the Search button) after you've entered a piece of text.