Consider the fact that sometimes, MDs see other MDs after hours without a paper trail in the EMR.
As long as the MD kept his own paperwork, this isn't against the rules.
For what it's worth, they do this to protect the other MDs privacy but also because medical boards can be nosy little ****ers and those records can be subpeoned to make a case against your safety as a physician. For instance, if you've ever seen a psychiatrist, it's always better if your psychiatrist's note just says "patient has anxiety. Describes frequent worry and panic attacks. Will give one time script for Ativan" instead of all the detail you'd expect in the EMR.
Now if the MD makes a habit of prescribing benzos for all his friends/colleagues, that's a different story. But a one-time thing I think you have consider that perhaps the MD saw the patient