I Have Had A Strange Sensation That Has Happened Once

I have had a strange sensation that has happened once maybe every 3 months, for my entire life. It is a very short episode, lasting about 20 seconds each time, and usually it is when I look at the face of someone I know well (such as my sister or my significant other). I briefly feel that, though I remember our entire history together and all of the memories I have with that person, that it wasn't me that experienced those things. That I know the person and our history, but don't know how I know it. These episodes so not seem to be linked to stress levels. They often happen while sitting on the couch, driving in a car, etc.

I recently read about dissociative tendencies, and it seems to be close to what I am experiencing. Since reading about this, it seems to have happened more often, though I recognize what is happening and the episodes end more quickly when I am self aware.

Should I be worried? Other than these odd episodes, I don't really feel any other implications from this. Should I see a professional?