What to do when a player goes south?

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I was playing a LIMIT game (10/20 omaha8) at a casino today. Some guy was going on a good streak and built his stack up to about 600 or so from 200. The guy next to him repeatedly kept bringing out black chips (100) to breakdown, which the guy on a streak kept changing for him. He ended up with about 5 black chips. And in about an 30 min after he had changed the last of the guys chips, they were mysterially gone from the table! Now, in this room all the omaha players were all pretty friendly with each other, and this guy seemed to be a regular and friends with everyone else, so I doubt they would mind. I guess what I'm asking is, should you call someone out on it? Even if everyone at the table gets along with the person? I wanted to say something, but didn't wanna get the scorn from him and create some sort of bad atmosphere at the table.