Every once in a while I will remember a dream but I can’t quite place when it happened, though I am almost(95%) sure it was not from the night before. It usually just seems to be from few weeks beforehand. They just pop out of my memory. These dreams don’t feel like the dreams that I remember from the night before either. Somehow they are special. I was wondering if maybe they are lucid dreams I am remembering but don’t remember being lucid in but just remembering the dream?
Why do you call them special? Interesting content or just the way they are recalled days later? 
IMO they probably weren’t lucid (unless you have a LOT of low lucid dreams) but the recall was triggered by something you saw or thought on the day the recall occurred.
Used to happen the same for me - when they’re recurring dreams. (well not anymore, since i’m keeping a detailed DJ). One, for example, was me going up a slope and descending the other, snowy side, with other stuff inbetween.
Other than that, i pretty much believe there’s no real reson to call a dream “more special” than another, except for its vividness. (and if it’s recurring, maybe it could carry a particular important meaning to you)
Another thing, it could be a FM that was used for a dream. I once had a dream about getting back the results of an art test i would have done a week before, and i was totally certain i had that test even if i did not dream of it. It took a while to convince myself, and thank heavens it was full summer (so there was no way it could have been true).