YEP, this IS an aspie thing, and ANOTHER wierd thing I do!
I will OFTEN go off on tangental conversation. It seems to be rarely appreciated so I now tone it down somewhat.
Besides, I am a programmer/consultant. I can't very well tell them everything, now can I. 8-/
I would go back to old conversations even years later because I wasn't allowed to finish, or thought of something. Even up to HIGHSCHOOL I did it all the time. People think it is wierd though, so I try to avoid it after an hour or so(it depends on things). Even NOW though, I may go back to it at the first opportunity!
I don't really know why it is considered odd. A person may ask a question, and I will give them some history, etc... I might start to talk about related things. That MIGHT start to get a little involved. Then they might say "STEVE, I just want a yes/no answer!"! Hey, maybe there ISN'T one! They may say something that sounds innocent, and the next morning I review things(I guess that is ANOTHER aspie trait), and realize that they misunderstood something earlier, and they have no understanding of what was said. EARLIER, I would correct it that morning. NOW, I often wait for the mistake, and tell them where they messed up, or I do it myself if possible.
Steve