no problem in that, because when you leaving the Id text box and placing the Cursor in password field then Post back occurring.that means the page is fully loading again.
so, all controls are reset.
that's why you need to click 2nd time for the password value.
you can resolve it using javascript/jquery/Ajax etc
one of the above solution..
See this Answer..
http://stackoverflow.com/questions/7322906/set-focus-to-any-control-after-postback[
^]