Writer's Condition

So I'm sitting here, trying to work on a web page and I'm half listening to a conversation in my head - between the two main characters of the novel I wrote last year!

I've been thinking a lot about the two of them, since they are going to be in action again in a month when NaNoWriMo starts - the new book is going to be a sequel.

And now they are already alive in my head... talking to each other! I hope that's a normal writer's condition or I'm in trouble. :-)