Note Macro renders incorrect html for message icon when wrapped in a user macro

When the Note macro is wrapped in a User Macro..

Output when wrapped in a user macro
<div class="aui-message warning shadowed information-macro">
<span class="aui-icon icon-warning" />
<div class="message-content">
<p>a big note</p>
</div>

Output when not wrapped (notice an actual closing span to close the icon span)
<div class="aui-message warning shadowed information-macro">
<span class="aui-icon icon-warning"></span>
<div class="message-content">
<p>a big note</p>
</div>