This just started happing on my discourse install (self hosted). It reporting this for all the rss links
e.g
<link rel="alternate" type="application/rss+xml" title="RSS feed of 'Is there a performance penalty in calling an external FB script?'" href="https://forums.finalbuilder.com/t/is-there-a-performance-penalty-in-calling-an-external-fb-script/6238.rss" />
These links are on every topic page, perhaps it might be be better to just let google index the rss feeds?