Is this concept often mentioned in mainstream media? This is mentioned a lot around here.
My hypothesis is that a "hn-bias" makes commenters more likely to mention it because they learned here that there is an explicit concept to arrange these funny coincidences, and moreover there is some quantitative work that has been done on the subject.
But it could be a variant of frequency illusion/Baader-Meinhof phenomenon (what would be its name?).