When using the default mousedown event, if the user clicks on the rippled element and (without releasing) drags the cursor outside the element, the ripple just stays there and doesn't disappear like it's supposed to.
Codepen example:
https://codepen.io/7oot/pen/OEgmML
After a few clicks & drags, you'd get multiple ripple containers stacked on top of each other and all disappear after a normal click & release.