It was in some random epub I saved in 0.5.3 and opened in the beta - the title should be empty, but was filled with that at a later save.
I tried to replicate it, but this time it ended up with :
Code:
<head>
<title/>
<link href="../Styles/uhhstyle.css" rel="stylesheet" type="text/css"/>
</head>
I've also noticed it randomly inserting <mt>, without a closing tag - I have no idea what causes that.