Thank you for trusting your question to JA today. I am a licensed attorney with over a decade of law practice and over 20 years of experience in the legal field. I’m happy to be of assistance.
As for legal charges, no you should not be concerned about that. There isn't a law that you've broken here and if the GM and HR director have an issue with prior policy, they can just change it. Legally, they have to recourse against you.
Now, as for disciplinary, that will depend on the nature of your employment. Is this a union position? Do you have an employment contract stating that you can only be terminated for cause? If you response yes to either of those, then any disciplinary action taken against you could be fought in court, based on lack of "cause." However, if you answer no to both, then your employment is "at will" and you can legally be disciplined or even terminated at any time, with or without cause. In an "at will" situation, if they wished to discipline you, they could do so.
If you have any further questions, please let me know. I invite follow up questions, so use REPLY for those. If you have no further questions then good luck going forward and please do not forget to rate my service with a top-three rating so that I receive credit for working with you today. Also, feel free to request me in the future, if you have questions concerning a different matter.