It's not necessarily a bad thing, though. While their rivalry is part of the fun, there are only so many different ways they can taunt each other without getting repetitive. Not that it has, of course, but I like that their relationship is progressing. It's almost like the more they taunt each other, the less they actually need to. You Kill Me was like a restart of the rivalry which hadn't been seen much since Lab Rats. Interestingly, their interactions have been more serious ever since For Warrick. Although they didn't have a scene in that episode, they sat next to each other at the funeral, so I can make reference to it. Consider 19 Down and One to Go. 19 had a scene between them that was more about him ignoring Grissom, and in One he goes to her as Grissom is leaving. Those are both more serious things. And while Space Oddity also played on the humorous aspects of their relationship, there was also a small undercurrent of a more serious consideration of their feelings. Mascara had a very small scene that was almost the normal flirty banter, but it was so short that it felt to me like it was almost like a way of pointing out that that relationship still exists, but in a smaller sense.
Okay, I think I might be getting way too analytical.