In rehearsals for a production of American Idiot musical and this reference to “concert” is in the score. My guess is this means male parts should sing in the written concert pitch instead of an octave below, but I am not sure.
You made a logical assumption, I can’t imagine what else it could mean other than concert pitch. Sometimes scores for musical theater are reductions and/or are written to be as practical as possible for a conductor or piano/conductor. Ask one of the vocalists if you can have a peek at his book, that should give you a definitive answer.