The two snippets below are identical except for the line breaks around the content, yet they produce different output in the browser. The line breaks in the second snippet affect the horizontal spacing of the labels, as shown in the images below.

It specifically seems to be related to the line break that comes AFTER the content, as demonstrated here: http://jsbin.com/dufiquge/1/edit?html,output.

<div class='label label-primary'>label 1</div>
<div class='label label-info'>label 2</div>
<div class='label label-success'>label 3</div>

<div class='label label-primary'>
  Label 1
</div>
<div class='label label-info'>
  Label 2
</div>
<div class='label label-success'>
  Label 3
</div>