Clearly we saw things differently. The point of all that was to show that in the beginning Sara did try to reach out to Tina but was shut out. And from Sara's demeanor I do think she feels guilty about it, or at least remorseful; but four years ago she didn't have any reason to suspect Tina was having problems. We don't have any backstory to fully see what happened to Tina, but a crying child isn't really a reason to be overly concerned. And she, and the viewers, have to assume that Nick or Greg or Grissom or Brass or someone else would also stop by to check on them. Four years ago Sara was in LV in the aftermath of Warlock's funeral. We don't really know for how long since there was a time jump from episodes 1-3. I guess she could have been more specific and said she was there 3 years and 8-11 months ago, or whatever. Focusing on Nick and Sara was more of a way to approach the story from both Eli and Tina's POV. I thought it worked well.