iTunes weirdness

If you use iTunes, maybe you can clue me in on something. Is it normal for random songs that I've never heard of to pop up in my "library?" I only use iTunes about once a week, when I have opportunity to go into my office and close the door and get stuff done while someone else is wrangling my kids. Today was such a time and there they were, random songs from various genres and almost all were from artists I had never heard of.