<p>As <strong>Procrastinator</strong> was kind enough to mention in comments, this is standard practice when a user has deleted him/herself while the bounty was open. For further reading, consider these links: </p>

<ul>
<li><a href="https://meta.stackexchange.com/questions/115503/destroying-a-user-can-leave-a-bounty-open-on-a-deleted-question">Destroying a user can leave a bounty open on a deleted question</a></li>
<li><a href="https://meta.stackexchange.com/questions/63873/why-was-this-bounty-awarded-by-community">Why was this bounty awarded by community?</a></li>
</ul>
