Is it normal that I get unaligned checkboxes using Bootstrap's example code?

I downloaded Bootstrap 3 which contains various examples, including a blog example. I used that and as a test copied verbatim the basic form example from getbootsrap.com into the blog post. Here's the result:

As you can see the checkbox label is not aligned properly (tested with Firefox and Chrome):

On the other hand the same code aligns properly on getbootstrap.com:

What can be the reason of this? I thought the given examples should work out of the box without issues.