I started to watch the anime some time ago and I'm only in the episode where Shampoo joins the series, so I don't know yet about her and Mousse's anime relationship. Though I have heard that she indeed does treat Mousse a bit more warmly at times in the anime. I'll see that when I get there.
But if I recall correctly, Cologne mentioned at some point in the manga that it seems that Shampoo doesn't hate Mousse as much as she used to...