I am a lawyer in CT and practice in this area of the law.  If the officer did not issue your friend a ticket, then he is technically not charged with a crime yet.  The officer may have done this to scare your friend and didnt want to bother doing the paper work.  I do not think that you have to worry right now as no criminal action was taken.  If you are still ocncerned, your friend can call the police and find out if there is a warrant out for his arrest.  if no warrant exists, then there will probably  not be any warrant issued and you can chalk it up as being lucky!