well i mean what happened? you extended your hand to shake / slap his and he just ignored it?
in my gym we all slap and fistbump before doing pretty much anything: partner warmups, drills, sparring. but maybe your gym just doesn't do any of it? if it isn't something the people at your gym do, then don't sweat it. it's not like you're missing out on anything. but if everyone does it and the instructor ignores it or he does it with everyone but you... then you got a problem.