Got suspended for not letting supervisor that someone was stealing from one of his stores?

i work for mc Donald's for over four years, one day my brother, a friend and me went to another mc Donald's to say hi to a friend, they were already closing and my brother ask him if he can have some pies, the employee give him the pies and by this time the manager on duty didn't said anything so i thought was ok because they had already close and they were trowing that to the waste, next day i heard that the employee and manager got fired for giving out two pies and apparently it was my fault too because im a manger from another store and didn't no body know what were they doing, so i went to day almost a week and my supervisor told me that i should let him know and as a manager im representing mc Donald's, thought it was stupid first of all i wasn't warring my uniform and i didn't took anything do think he is correct i should i do something please help me out