Modal position changes after re-opening

Hi Cole, I noticed that after I click into the modal box, then exit it, and then click into it again, the position changes. This is with zero edits to the modal position. See below:

First open: http://cl.ly/PqRO
Reopening after closing: http://cl.ly/PrCl (much higher)

I think you need a better method that keeps the modal always exactly centered.

http://wordpress.org/extend/plugins/wp-modal-login/