The only rule I am aware of that is close to this is:
6. When linking to outside websites, you must ensure that the content of the link is appropriate for our community, in line with the guidelines laid out here. This includes mentioning or referencing a site, even if the mention is not hyperlinked. If you post a link and that link is automatically censored, it is considered to be an inappropriate link and you should remove it from your post immediately. If left, all posts that feature inappropriate links may be removed.
Linking to a sign-up, teaser or members-only page of another site is not allowed. These posts will be removed.
And I am not sure how someone mentioning what they saw would some how violate that.