Thanks KoRn! Whew, that was close! ;')
Jupiter has over sixty moons, most of which are small, and many of those move in retrograde, which is often considered diagnostic of capture. There's such a narrow window for capture -- lies between ejection and swallowing -- that these events are probably commonplace, and have been (on Jupiter in particular) throughout the existence of the Solar System.
Or (knowing wink to list) throughout the time Jupiter has existed in its current form...