Definitely looks abnormal, but could be a piece of dirt or something. What type of substrate do you have him on?

If you wanted to be safe in the meantime place him in a sterilized, plastic tub or glass tank and use paper towel or white paper as substrate. Have 2 hides and a proper sized water bowl. You could add a plant or two, maybe a fake stick but keep it minimal(avoid adding in real wood). Check daily for any black spots on the paper towel or in the water bowl. Also check your snake out to see if these black dots are appearing more frequently and if they progress to different areas around the face.

If this is a case of mites it looks like you caught it quite early which is good. Just keep an eye on things and make sure your snake has a water bowl big enough to soak in.