was wrong of shane to celebrate on the roll, very out of character and very APA like of him. But it was worse for Cheng to do what he did. It doesn't matter that shane wasnt down on his shot, he seemed to have done it in order to get shane a bit riled up. the above comment is correct, technically, there is no rule against it, but it is unsportsmanlike. In local leagues, sometimes ppl have to take a look at an opponent's shot to make sure whether or not to ask for an unbiased set of eyes, and even then its still rare to see a person leaving his table area to look closer at a shot when his opponent is at the table. But in a tournament with a ref watching the whole time, it is unnecessarily to walk to the table when its not your turn and therefore Cheng knew what he was up to.