What is the appropriate use of the Article element?

I want to change

<section>
  <header>...</header>
  <p class="tweet">This is a tweet preview. You can... <em>6 Hours ago</em></p>
</section>

into

<section>
  <header>...</header>
  <article class="tweet">
    <p>This is a tweet preview. You can... <time pubdate>6 Hours ago</time></p>
  </article>
</section>

But after reading some articles on the <article> tag, I'm not sure that this is the best move. What would be better practice?