To you a song is nicked if you can sing the verse of another song on it.
In music there are just those melody-lines that match. That is not nicking, that's just the way that melody goes. And yes, sometimes the match is obvious but still that is not always nicking. But as well as this time and all the times before I tried to tell you that, you won't believe it.

I salute you,
Thunderstrucker