If anyone else was nearby playing, I'd suspect that to be the case, and I'd back off. My only concern would be that I've seen people in high limit rooms playing a handful of machines at once, basically loading them all up and playing them back and forth. Not that that's what I would have necessarily done. Morally, sure, the 'right' thing to do would be to contact an attendant who can look up who played the machine last (after all, someone playing hundreds most likely either had their card in the machine or was being tracked by an employee live). This makes the Bellagio Casino the fourth largest casino in Las Vegas (The Wynn and Encore are number 1 in Vegas with a combined gaming floor of 191,424-square-feet). Since there's really nothing done about that, I'd suspect there'd be nothing done about this, either. The Bellagio Casino boasts over 116,000 sq ft (10,800 m2) of gaming floor, including the famous Bellagio Poker Room. In Atlantic City there's a big problem with homeless people coming in from the Boardwalk and cashing out slot machines as soon as people leave them.
Just as if you found a casino chip on the floor - you're only using the chips as representative tokens of money for that casino, and they are property of the casino. The 'official' rule is that when someone leaves, it's the casino's money.
