Jack, I think you're right, and what you're describing is common to a lot of magicians. I would go further and say it's probably common to writers, artists, musicians, and creative people in any field. Having dabbled in writing and music production myself, I can definitely say that there are times when it's almost impossible to stop, and I almost feel like it would be a waste of the creative urge if I was to do anything else. I would describe it as being the opposite to writer's block.
However, I think this burst of invention and creativity is a different phenomenon from the need to have cards with you at all times and keep running through your sleights. I think that is more of a habit, based on repetition, rather than a process of creation. And, I think this habit, or addiction, is probably essential for the finished card worker. If your subconscious is making you run through your sleights without you necessarily deciding to do so, it means that, in performance, your attention can be turned to presentation, misdirection and generally being entertaining, while you let your well-trained hands do the work for you.