After consulting my 2004 Scott catalogue I keep in the office. The stamp in question has a dot above the first 's' in the word 'states'.
Scott lists two plate numbers having this variety.
Plate #18774, LL 9
Plate #18773, LL 11
I'm glad you asked this question, as I hadn't noticed the reference before.
I'm curious ... why isn't this variety listed for a single stamp

(Scott 629).
Brian