When it comes up again in a minute, I will put in "your" as demanded, but I am going to report it as "my answer should be accepted" because although I agree "...on your face!" is the usual way to say this in English, contrary to what has been said in the previous discussion mention of something on a body part (or clothing) is sometimes used in English without the pronoun, e.g. "you've got a spot on the arm" or "I've got a mark on the trousers".
This has come up again as a "crack" exercise, and I have reported it again as "My answer should be accepted". English in England anyway does not "require" a "your" - it is usual, yes, but not compulsory or universal. If the statement follows "you...." who else's face would be on?