oh man i hate it when i get on a little run and the dealer looks at me like i should tip him/her. yes, if i were up big i'd give u something but no one gets squat until i'm actually up money. i just hate it when u make a little and they expect u to tip them without realizing or considering that before i won this 500, i lost 800 an hour ago. just cuz i'm on a run now doesnt mean i'm actually up any money. no one gets anything until i am.
but OT, he probably felt 100 was too much of a tip. if the guy gave him 20 bucks he probably woulda taken it. its really up to him if he wants to take it or not. there's no proper answer or etiquette/rule.