For some reason I always thought that Rick Astley's song I Want To Give You Up was a song from the early 70's. Probably cause it reminds me of Gino Vanelli's I Just Want To Stop, I thought it was 70's as that song was as well and both seem to have something about them to be common. However, I Just Want To Give You Up was actually released in the 80's even after I graduated High School.
Then there was Union of the Snake by Duran Duran, that I thought was released in the 90's but again that was an 80's hit. I never heard much of that song as it was one of those that faded after it dropped off the charts unlike Rio which still to this day gets airplay, so I had nothing to compare it to in time.
Then there was the opposite where I would think a song is new, but actually old. For example Chris Rea's Fool If You Think Its Over I heard after moving to Florida over the radio here, so I thought it was a new song or a late 80's song to be the most recent. The sax on it sounded like Kenny G, and Mr. G's popularity came in the 1980's as well with Songbird, so that may be why, even though he never actually played for Rea just a coincidence that Rea's musician sounded just like Kenny.
Have you ever got songs mixed up this way thinking they are a 70's disco or something and then finding out later it was an 80's or 90's tune?