Don't want to sound like a troll here, but honestly with that kind of action with a flush flop, did you really expect to have the best hand? Not faulting your play at all, and while it is rare to have 3 people have a flush, not totally unheard of.

As for the odds of you being cheated, I would say precisely zero. Worked at casino's before and something like this is would require the total and complete ignorance of security in the casino as well as the dealer at the casino being an inside man. If I was a dealer and wanted to make money stealing from my employer, there are far less involved and far more profitable ways to go about it.