Do you ever got horny seeing other people making out?

It was weird that it happened to me for the first time in my life yesterday when I got out from a railway station.There was this narrow alley behind the station where I saw a young couple making out.For some reason it aroused me and I was thinking about it and sex all day.Now it's making me feel weird for wanting to have sex just because I saw some strangers making out.
Ever felt this way before?