correct me if i am wrong but last time i checked, photographer's rights in most countries state that any photo a photographer takes in a public place becomes the property of the photographer, not the subject. as long as dude is okay with people using his photo and they ask permission there isn't any real reason for this to be a a weird thing, especially since it seems like everyone is only enjoying it on a personal and private level. go through your photos, i am sure you have hundreds with background characters who have no idea you have pictures of them, some of whom you have probably never even met. it doesn't matter, because the photographs belong to the person who took them.