EDIT: I got it to happen again, and this time it took much longer than 5 minutes.
I've sort of noticed it happening before, but I wasn't sure, and even assuming I was correct I didn't have an idea of how long it took. With my first comment to this question, I am sure it happened, and fairly confident that it was 5 minutes after the comment was posted.
Why does the site change how it displays comments? (after whatever period of time)?
Is there a way to see how the comment will be displayed without just waiting?
I managed to get a before and after (though not for the comment that caused me to make this post):
The top comment is the after, the bottom comment is what it looked like before.
(If you go to that question, you won't see the image's bottom comment, since I deleted it due to it being a copy of my first comment there.)
My original comment there did look like the image's bottom comment even after I waited and reloaded.