Senior citizens..Do you find yourself dwelling in the past?

When I was younger, although I loved my senior family members, I was turned off about how much they seemed to live in and talk about the past. (Im not talking about anyone with dementia or memory loss). I listened politely but promised myself that I would not do this when I was old. Now that I am a senior, I find my thoughts much too often returning to past events. I hope I can explain this right... not at any specific time, nothing i consciously do, but for example I can be at the computer typing an important letter and out of nowhere get a thought about being in my Grandmothers kitchen.. actually seem to smell and feel everything around me to the smallest detail.. It doesnt matter at all whether the image or thought I get is positive, negative or neutral. What surprises me is how vivid it is. I can spend some time with it, or push the feeling or image away, depending on what Im doing at the time. Otherwise my life goes on normally. I am hoping one of you good people out there can share whether this happens to you, and what you do with it. And do you know why this happens? If it only had one theme I would think it was something unresolved, but it doesnt. It is random. Thanks and bless you for any insight you may provide.