I'm having a problem with sporadic unwanted space on the right-side of a responsive email rendered in iOS 5 Mail. Here's a screenshot. The email renders correctly in iOS 5's Safari and in iOS 6 (and later) Mail.

If I remove the <img> it performs as expected - the white-background table fills like it should. But if the image is present, the extra whitespace appears. Similarly if I replace the image with an <a> the problem remains. It's like any HTML element inside of the table causes the problem. More puzzling is that previous issues of the same email newsletter which include images, text and links render 100% correctly with no extra space on the right. There must be something in the bootstrap or the media query I am overlooking.

Here's the HTML source for the most basic setup which exhibits the problem.

Any ideas would be appreciated. Thanks!
Jeffrey