Sara, after being close to death, is experiencing that rush of "carpe diem" with her more aggressiveness in police work, and in her personal life. Grissom's reaction to her advances was pretty amusing.
This is all pretty lame (unless real life personnel events dictates it - like did y'all notice that Jorja Fox was showing her pregnant belly on last night's episode). Plus, CSI is the #1 show on TV (by 4-5 million viewers each week over the #2 show and below), do they really need to resort to...