The rules of the game are not in the code. If the bug would be the other way around, where it would suddenly payout 82$ if you'd press this sequence of buttons, the casino would definitely return the money.
It's like giving money to strangers. If you surprise them by giving them money that's OK, it's your money. If you surprise them by stealing from them, that's not OK.
So a game that surprises you by giving more winnings than expected is fine; a game that suddenly reduces the winnings by taking some of the money you've won is not fine.
Or another way: Sometimes I feel generous and forgo a customer the decimal part of their bill to save them trying to find the money or if they haven't enough, that's fine, it's my "game". I can't decide to take their change though.
When the giving more is built in to the game, so you play it a a particular way and the you win more, that's just a game that you're winning.
