Tunnel Vision at Nostrand Avenue

You too can see this odd little thing on the lower level of the Queens-bound platform, in the Nostrand Avenue subway station on Fulton Street -- where the A and C trains stop.

That's a nice bit of tiling, eh? But what's that little rectangle right under the letter A in NOSTRAND?

It's...a...

...it's a photo of the same bit of tiling! Glued to the tile. How very odd. If anyone can give some insight, please get in touch.