jiggling the handle of OS X 10.8.5’s dock

About once a week now, I’ll notice that the Dock on my Macbook (running 10.8.5) no longer auto-shows itself when hovering at the bottom of the screen.

My current somewhat-quick workaround to make it behave is to four-finger-swipe-up to activate Mission Control, which shows the Dock. Then right-click on it and open up the Dock preferences. At this point the Dock is behaving again; close the preferences.