Car sold to Poland, now comes buyer with alleged damage

Hello! On 20.08.2019 I sold my Audi A4 B8 Bj 2009 via mobile to a Poland. He took him after five hours of journey and a short test drive around the block. All right so far… Yesterday the news came suddenly via WhatsApp that the car would probably have had a hail damage and the whole spatula would have torn which he now has to repair for 300,-€. I was not aware of any damage, I have the vehicle with 90tkm in 2011 and now with 200tkm sold and visually no fahler seen in the paint. He now threatens to come by tomorrow by car, after he offered we could do 50/50 and later even went down to 100,-. Of course I did not consider it, especially since it would have been the easiest for him to send pictures of the damage, he did not make and I also do not want to ask about it. I assume that this is a trick, in order to pay even more money in the following ommen. Have you heard of this before? What if the guy is really standing at my door tomorrow? Does he somehow have the right to demand something from me? Even if I don’t assume that he can return the money to the gas station right away to drive home.