Puerto Rico old stamp, Scott #111 I believe.

200% zoom, sorry for out of focus.
Looks to me like a piece of paper got on the printing press and created the 'dot on T' of Puerto.
(ooh, maybe also on the '5' I now see?)

I personally like the misperf-ness of the stamp, but to each his own.
Comments on possible value or causes of welcomed. Mint hinged.