<p>It's not a bug.</p>

<p>If your flag weight reaches 500, the calculation turns from linear to asymptotic, eventually reaching 749.99999 (or maybe 750, if you're lucky).</p>

<p>See also: <a href="http://meta.stackexchange.com/questions/80170/what-is-flag-weight/80178#80178">What is flag weight?</a></p>

<p>Maybe it should be rounded, but this display gives you an idea of what you're heading for, if you keep raising great flags :)</p>