facebook comments and likes privacy?

[Reystina]

While I'm browsing my friend's photos, one of his pictures says it has 8 likes.But when I counted the actual number of persons who liked it, it appeared only to be 7. The same thing with comments. There's this one picture that seems like my friend is responding to someone's comment, but that "certain" comment is not visible. It's like my friend is talking to himself. I'm wondering why and how do these happen. Do you think I am blocked by that "invisible" person? Or is it me who blocked him, that's why I can't see his name on the "like list" or on the comments? Please respond. Thanks..