I am not at all certain I would make a false accusation of wrongdoing against a guy who could produce his calendar from 1982. Very organized, always has been.
I learned the lesson early on how important it is to keep a log of your time. It doesn’t have to be altogether truthful, in fact it doesn’t have to be truthful at all, but if somebody comes at you later with a vague accusation and no evidence, something beats nothing every time.