Hover box does not fade away on iphone

This is a great plugin but I’m having a small problem. When I go to my website on an iphone and tap the highlighted word to elicit a hover box defining the word, the hover box never goes away unless I navigate away from the page or scroll all the way to the top. This happens with browsers Safari and Chrome. With an Android smart phone, the hover box disappears when you double-tap the screen (Chrome browser). No problems with plugin on laptop.

Thanks for any help!
Chris