careful...
unless this was a tribal joint out in the boonies, likely that overpay was discovered. the discovery should have been no later than the next (checque rack) count, usually before the shift change...= "close". it would be surveillance's responsibility to rerun all tapes until the shortage was spotted. first suspect would be the dealer. then the table fills and markers (if any), would be checked. any surveillance agent worth a sh*t would notice the overpay. if the amount were significant, depending on the sweat factor of the joint, likely the dealer would be fired. and, depending on how much juice the pitstiff has, he/she as well. pitstiffs are required to "approve" all color-ups, checque changes, and buy-ins.
a similar situation has become public, in a slot department. a fellow was playing a newly opened, "locals", west side joint when he noticed that a slot was overpaying all wins. apparently there had been some switch of circuit boards, between adjacent machines when they were being installed. the fellow "won" well over $10k. the error was discovered. the fellow returned a day or so for another shot at the same machine. he was recognized from surveillance tapes and detained for gaming investigators to arrive. i don't know what finally happened as to criminal charges. bottom line, if you were to keep the overpay, for sure i wouldn't revisit that joint, any joint owned by the same corporate group, and any joint which because of geographic vicinity, might share information between surveillance departments.