ITunes issue when adding music?

I haven't had any issues with iTunes the last few months but for the past few days I've had the following problem. I know you may not find it a "major issue" but it is really annoying.

I have all my music in the iTunes library, but of course NOT All songs in the library are on my iPhone. Recently I added more songs to my library and again just selected certain ones o go onto my iPhone. When I drag the file or files over to the phone to be copied, it starts "updating" my phone and copies over about 40+ random songs which I deleted from my phone a while back.

Can anyone help with this. I have not changed anything recently apart from the software update on my iPhone.

If you deleted the songs in your iPhone but you don't delete the songs in iTunes Library then every time you update your iPhone then the same songs will end up on your iPhone. That's how it works.