This has been happening to me on and off the last ten years or so, smelling the scent of roses.
It always happens at home, and not the same home, I have moved a number of times.
The scent doesn't stick around long, maybe ten seconds, sometimes a little longer. Always long enough for me to get in a few deep breaths...kind of like making sure that I smell it. Its hard to describe, but I'm trying my best. 99% of the time I am alone. I find the scent comforting, gives me a warm fuzzy feeling...then its gone.
Does anyone know what this could be?