When I enter into my writing zone - I experience something similar to John's story. Days seem to literally melt into weeks. Before I know it, people start complaining I haven't been in touch for a while. LOL
This post also explains the phenomenon that most experience when I facilitate an event (class, workshop, seminar, retreat, etc.). Event feedback forms consistently document "how quickly their time went."
When we're doing / being what we love with others who love being and doing the same - time fades. Space grows. A taste of the eternal teases us for a moment. Yes?