Skepticism is of course healthy... but the frequency illusion thing may not be applicable here.
For the "frequency illusion" to be a valid here, someone somewhere is independently rediscovering the meme, and posting it for friends/strangers/whatever, right?
Where are they coming up with it though? It's not from primary/original researcher. They are seeing or hearing other references to it in their social lives. Even if that happens offline (which I certainly hope still happens), then the person they received the meme from almost certainly got it from one of the sources you yourself noticed earlier.
Now, because of the way the transmission worked, you missed several links in the chain. But you're still seeing the outline of the chain, even if you're missing alot of detail.
Superstitious people think that seeing something everywhere means it popped up because of some supernatural forces or whatever. But I think it pops up because these memes are flowing back and forth between brains, and if you're located in one part of the social graph, you'll continue to see it flowering in proximity to you for hours, weeks, or months.