I have a feeling if the manager came to your table and said: this is NOT accepatable and I will take measures immediately to ensure this is addressed at once blah-blah-blah it would have eased your mind.

My impression is your stance is to ensure this doesn't/wouldn't happen to anyone else and the manager may have had an attitude of OOP sorry we will give you the meal for free and cook up something else etc.

I think this may be more of an issue of how the manager responded and if he understood food safety importance. if he shared your concern I doubt you would be here right now. it all goes back to customer service and knowing how to handle situations with conflict/issues.