Have you ever recalled a dream, but you can’t remember if that was a dream from last night or last year? 
Its been happening to me lately. Since I started trying to have lucid dreams, Ive been remembering old dreams, some that are even years old. Whn I remember them, I feel like they were a long time ago, but as if they were from last night. Has this happened to anyone? If so, can anyone explain why this happens?
Maybe they are recurring dreams or your dream recall is just becoming that much better 
I know exactly what you mean. Ever since I got into lucid dreaming around two years ago, I frequently recall dream which I don’t know happened months, days, or even years ago. A great example would be when I read your post. Thinking about it, I recalled a dream I had involving changing into a Chinese dragon in some Californian home. I have no idea when I had this dream, but I remember it clear as crystal.
The same thing happens to me. I feel like those dreams happened a very long time ago, but I remember it almost as clear as real life. I can remember the conversations, the people in it, basically everything. Sometimes I’ll just be walking down the street, and the image of something in the street will bring up a dream, and that dream will bring up another. I think its really amazing how much I can remember now.
That dosen’t happen to me, but I know when my dreams take place. I usually only remember the dreams that I have that particualar night.
I agree with shortbirds. I think you may be having reoccuring dreams. Perhaps there is a problem you have yet to solve.
Sometimes I don’t recall dreams until I see something that is related to my dream in some way.
I’m not sure why it happens, but I’ve had some before. Sometimes I would have a dream and it would seem so familiar as if I’ve had it before but I don’t remember where it was from.