My DP came back last night from the local recycling centre proudly brandishing a picture which he says one of the people at the centre fished out of one of the containers for him. It's quite a nice picture. The problem is that there is a label on the back showing that it was sold by a gallery for quite a large amount. It's also very clear who the artist is both on the label and also of course the picture is signed. He is now talking about selling it but I am concerned that it isn't his to sell, given how he came about it and that he might get the person who fished it out for him in trouble as they aren't supposed to do that (there is CCTV at the centre). He says that is a worse case scenario and that I am being unreasonable stopping him selling it and telling him he should really take it back to the dump, but I'm concerned that this could come back to haunt him. AIBU to worry?