At this point GZ did not know if Trayvon had a gun or not.
no but George Zimmerman knew he had a gun, and it is not a huge stretch to suggest that the knowlege that he had a gun in case something went wrong made him bolder and more aggressive that he might have been otherwise.
but somehow we are supposed to believe George's story that the kid with the candy and no history of violent behavior was the aggressive one who hit first, and not the persistant following guy with a history of violent behavior in the past older and with more experience and with a loaded gun who only wanted to ask questions in an aggressive manner and keep the kid here for LE to question. IMO JMHO and stuff.