It depends on the bug. If you are not aware of it, it should be forgiven. But if it was a proven exploitation, then your account would be justified in being punished. Generally, if you know of some crucial bug, do not try to make use of it; eventually, you'll be punished for taking advantage of it. Be fair.
Now the question is how do they know the difference or be able to identify you being aware of the bug or not, how will a casino know your true plight and intentions not to harm or attack them, i think the best solution here is to completely avoid bug, they have a system that controls such and if you're suspected for one they or be friendly with you by any chance, once a bug is detected and does not relate to you or traced on you, you may be free indeed, but casinos are very detestable when it comes to issues on bugs.
If someone finds that bug and uses it to their advantage, the casino will find out about it sooner or later and punish that person for rigging the casino. But if that person reports it to the casino so the casino can fix the bug, the casino will not penalize you and may even reward you for helping the casino find the bug. Now, what is a person's purpose or motive after he knows there is a bug in the casino? Will he report it to the casino or use it himself?