The clock is not entirely bug-free and has been a bit of a victim of my impulse towards premature optimization. I've rewrote it once and I'm considering rewriting it again... so it's not just you. It should hopefully work properly if you reload the page.
For some reason I never seem to encounter bugs like this myself! I guess I'll have to do another rewrite of that. Was it just the menu clock? Did the clock app exhibit the same behavior?