Oil leak

That is typical of the majority of cars and there is nothing you are going to do about it other than to spray the area off with Engine Degreaser if it really bothers you. That little dribblage ran out of the passages when you removed the old filter, and made that area wet. Some more conscientious mechanics will attempt to wipe that residue off, but it is impossible to get all of it. The rest will dry up and vaporize after a few days. If you see spots on the floor a week later, then we will need to discuss the possible causes and solutions.