Yes, Andy has played Novak twice on grass, the Olympics and Wimbledon. Andy won both in straight sets.
People could be pedantic I suppose, saying that the Olympic semi was 'only' a best of three, but my argument would be that yes, but Andy won two of them, so he won the match. What you really can't argue with is that Andy won the Wimbles final, also in straight sets, albeit three tough sets.
Again, people could point to the fact that they've only ever played twice on grass. I would counter that by saying that isn't Andy's fault, and neither is it Andy's fault (although I suppose it is really
) that he's a better grass courter than Novak. To me the way Andy's team hoped it would be Novak in the final rather than Delpo, just about says it all.
You'd want to check the figures, but I worked out that during their Olympics semi, Andy won 54-55% of the points in both sets, and it was similar at the Wimbledon final.
For all that the Olympics felt like two tight sets, and the momentum during Wimbledon swung back and forth, Andy seems to be just enough better to make the difference.
Regarding Novak saying he was glad Andy won - I don't buy that either. I accept he may have been happy for him, but no player is ever glad they lose. He has excellent English, but perhaps it is easier to come out with those platitudes when it isn't your first language. It's more of a script of the right thing to say than what he's feeling. Even if it is a bit fake, it's better than being ungracious.