Calling your crush SIR, who has been your boss once?

how do guys feel if a gurl addresses them as sir,who has been her boss once n is no longer her boss now? i knw this guy where i interned for 2 months.. i started liking him .. n he likes me too.. he gives me tht hints.. hes a shy kind.. so he doesnt give any direct hints though.. we havent confided into each other yet tht we like each other..hence, i still address him as sir.. i wud want to knw do guys like to be addressed as sir from the person they like? or they rather like it if they call them by their name only?