I've never experienced it in real life, but it seems common to writers and for all the same reasons. Once the flurry of contracts, edits, cover art, the release and post release promotion is over, there comes a pause when nothing is happening. You've responded to all the comments and the spike of hits on your website and blog is fading back to the background level. It is too early for the reviews and you try to concentrate of your WIP...with little success.
It doesn't seem to matter how many times you've been through it, or the resolutions you made last time. Time slows to a crawl and you can do nothing but wait until it passes.
Am I the only one?