This is what I do and what happens:

1. I click on the reply button
2. While I'm writing my post a moderator delete the last post in that topic.
3. I submit my new post but the post is not placed directly. The page where I write my post is actually reloaded.
4. When I hit the submit button again the post will be placed.

I think it is ok that the page is reloaded but then the user should get a notice that the last post is deleted (just the same when someone already made a new post).

And it happens only when the last post is deleted, not if a previous post is deleted.