Goodman says: "the predicate 'grue' ... applies to all things examined before t just in case they are green" (Fact, Fiction, and Forecast, p. 74) 
 Hilary Putnam says: Goodman "defines something as grue if it is either observed before a certain date and is green, or is not observed before that date and is blue." (Fact, Fiction, and Forecast, Fourth Ed., p.vii, Foreword) 

 I suggest we leave it at that, and not correct the original expression or logic.