I know that in the Supreme Courts 6th district there are published court documents describing what a contract with a patron and a casino is. I'd have to re-look up the exact wording. In plane old english it states when someone puts money into a slot machine, they have entered into a contract with the casino. As soon as the patron wins a "round" or "hand", the casino gives up all rights to the money being played. The responsibility and rightful ownership then shifts to the patron. When the patron departs from the game, or machine, the contract is settled.
You can argue that translation within the publication as abandoned property. As the patron has declared no rights to that machine (including the ticket inside) by leaving. I don't know where your at, but the 6th District is in the Midwest/Michigan....etc...