For smooth stroking, a lot of grease is used in the shell case of inverted type shock absorbers (Photo 1). Sometimes an oily discharge escapes via the vent hole at the bottom of the shell case (Photo 2), and is mistaken for an oil leak. Also, reducing its viscosity, extremely hot weather or heat from braking can cause excess grease to ooze from the vent hole.
In either case, if you wipe once or twice and it stops, it is unlikely to be an oil leak. If you really do have an oil leak, it will keep flowing regardless, and you will need an overhaul.
Furthermore, inverted shock absorbers have their oil seal inside the shell case, making them less likely to suffer an oil leak from external causes than upright ones. Also, if somehow the stroke part that is visible from the outside (Photos 3 and 4) gets a scratch, there is no reason for concern, because in case of inverted dampers that does not directly lead to an oil leak.