I think any woman who has been pregnant, or maybe is trying to become pregnant, can vouch for this effect - all of a sudden there are pregnant women everywhere.

Sadly the same thing goes for losing a loved one. You're hyper-attuned to the loss and tend to "see" them or recognize a common feature in people everywhere.

I guess it's an interesting comment on how much data actually pass us by on a daily basis, stuff we don't notice or recall.