I have a tooltip attached to a panel that can slide down on the screen when it is clicked. If I click that panel, the tooltip doesn't reposition, but if I then scroll any amount, the position of the tooltip fixes itself. The is true for their demos as well. I'm assuming there's a reposition function in the plugin, but i'm having troubles finding it.
If scrolling fixes the problem, then you can always trigger a dummy scroll event like this:
$(window).trigger('scroll');