I cast some undelete votes, with the undelete dialogue claiming I have 2 votes remaining. In reality, I have used my 5 undelete votes, and I am unable to cast any more. The "Vote to undelete this post?" dialogue box is incorrect.
Information about votes is not always updated in pages that you already have open. I've seen "misfires" when voting to close or delete when something changed since I loaded the page. (I think I've seen similar odd behavior with posts that became locked while I was trying to do something, but I might be misremembering.)
The general rule is that the server doesn't push everything to already-loaded pages; developers made decisions based on cost versus inconvenience. When in doubt, reload the page.