Here I just thought I was "obsessing". I'll think of things that occurred...situations, exchanges between people...for hours, days, weeks, sometimes even months after they've occurred. Then again, my memory stretches back to about the age of 18 months (verified by my dad, when I would describe things). I'm 27, and I'll still reflect upon things that happened as far back as elementary school. Could or Should I have done something differently? Ridiculous!
And yet, if I am interrupted mid-sentence or mid-project...I do get stuck, and I can't remember what the goal was. I'll remember it 10 hours later though! That point I was going to make...and then it's all I can think about, and I want SO badly to call up that person and say, "Remember how we were talking about such-and-such yesterday? Well, I was thinking...."
I find that writing everything down helps, because interruptions of thought processes are inevitable. I'm then able to re-read what I WAS so focused on, and hopefully jog some of that out of the back of my brain in a more timely manner.