i read ur post..and i can read into why ur questioning whether its cheating or not. i feel like the only reason ur questioing is because it was brought up.
no u werent cheating. but if knowing ur boyfriend would feel disrespected by the situation, just dont do it. the only reason u realized he would be upset about it is because someone mentioned it, then like i said, stop. mention it to him if u like. but to me.. it wasnt as if u set out to go do something like that.
if ur into him...respect him whether or not he is in ur presense.