I've called it red car syndrome for decades, but apparently to the world at large it's...
Blue Car Syndrome - a whole article there, but it's perfectly well defined in UrbanDictionary as...
The act of seeing or hearing something and then suddenly seeing it everywhere.
You buy a blue car, and suddenly you notice blue cars everywhere.
Technically, as ermanen notes, it's a type of cognitive bias called the Frequency Illusion.
